Super User is a question and answer site for computer enthusiasts and power users. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

Short description: I bought a new computer a couple months ago. My problem is that every now and then, my computer "freezes up". However, if doesn't freeze for good. After a couple of minutes it comes back to life, and everything's fine again. This tends to happen while on Skype calls (with and without video), and while viewing flash video.

Long Story: I basically bought all the parts for the computer, and assembled it myself (I have decent experience doing this, I don't do it for a living, but i'm not a total newbie at it).

This is the parts list:

  • Intel Sandybridge i7-2600 Quad-Core (3.40GHz, 8MB Cache, Socket 1155)
  • Motherboard: Intel DP67BG Extreme Series iP67 Socket 1155
  • Corsair CMX8GX3M2A1600C9 DDR3 XMS3 8GB Desktop Memory (2 x 4GB)
  • nVidia GTX550Ti 1GB - card by MSI - MSIN550GTX-1GCY
  • OCZ Vertex 2 120GB SATA II 2.5-inch Internal Solid State Drive
  • Coolermaster GX 650W PSU
  • TP-Link TL-WN781ND 150Mbps Wireless PCI Express Adapter
  • Using on-board audio card

That's the basics, I also have 2 "regular" HDD drives (1.5 Tb and 2Tb).

OS is Windows 7 Ultimate 64-bit SP1, with pretty much every update it suggests installed. I also tried to update every single driver to the latest version, and also the motherboard BIOS is the latest. I couldn't find an updated BIOS for the video card, though. I also have the latest version of Flash.

The sympton that I get, precisely, is that sometimes the computer freezes completely (mouse doesn't move, "Num Lock" light doesn't turn on/off, it seems to be completely dead). If you leave it like that, however, after 2-5 minutes it comes back, and everything picks up where it left off. All disk operations that were in progress continue normally, all programs seems to not know anything happened. The only thing that fails is that network connections obviously get dropped, but that's it. After this happens, there are absolutely no related entries in the Event Log. Not sure if there's anywhere else I could be looking. I've never had a blue screen, or any other problem other than this freezing that always ends up coming back to life.

This only happens when I'm talking through Skype, both with video and without, and (less frequently) when I'm watching Flash video (youtube, vimeo, etc). It also doesn't happen every time, or even most of the time, I've watched long videos and had hour long conversations without problems, and sometimes the same call drops every 10 minutes. So this makes it kind of hard also to see if anything has "solved" the problem, sometimes it takes a couple of days to fail again.

Skype fails way more often than Flash video, though. Also, this never happens, at all, if I'm not calling through Skype or watching videos. It's gone for days without any freezing. Chatting through Skype is not a problem. Flash games are not a problem, "regular" games (Call of Duty, etc) never hang. Listening to music all day is not a problem.

I've tested the RAM with MemTest, which says it's fine, plus I've removed each of the two DIMMs individually, and with each of them I still get the freezing, so i'm pretty sure it's not RAM. I've also switched them from bank to bank, just in case it was the bank, but they all fail similarly. But that's about as much as I've been able to rule out from the hardware side.

I also don't think this is related to overheating. I haven't installed any "temperature measuring" software (if you can recommend one, I will), but all the CPU, GPU, and motherboard heatsinks are very cold to the touch, all the time, even while playing large videos or gaming at maximum graphical settings. I haven't really been able to strain this computer at all, CPU is never higher than 15%, for example. I was able to make the GPU get a bit warm (not particularly hot) by running FurMark, and that also didn't make it freeze.

At this point, I'm completely stuck. I don't know how to find whether the rest of the hardware is faulty, or to prove it's not, and the same goes for software/driver. I also don't have spare hardware to start swapping parts on/off.

I'd really appreciate any ideas on how to figure this out, because this is very annoying, particularly because I constantly drop calls with clients, but the rest is so close to perfect that it's hard to believe this happens. I'm getting quite desperate here to be honest...

Has any of you experienced something similar to this?
If I'm asking in the wrong place, please let me know where I should and i'll move the question there.

Thank you very much!

share|improve this question
up vote 4 down vote accepted

Can you please try to do my procedure here and answer with a link to the trace in a comment, I'll look into it.

Just start to run it each time before you do a Skype conversation or watch a Flash video...

When looking at your trace I see several values spike up to 100% after Skype: CPU, I/O and so on...
I/O isn't really 100% because it just can't update the graph anymore because of the hang, so let's ignore that.

One of your CPU cores is up to 100% because of the System process, and more specifically DPCs.

So, right clicking on the DPC CPU Usage graph and going to Summary Table reveals this:

enter image description here

NDIS is the Network Driver Interface Specification, which indicates that network related stuff is going wrong.
This makes sense, because you are calling with someone over a connection or streaming a video over one. There are probably dropped or bad packets that are causing your device or driver to fail...

Thus, you should first try to do the following two possible solutions:

  1. Get the latest network drivers for your system, not from the CD. If you have latest, try an older version...

  2. Replace the network card if that doesn't help.

This should normally solve the issue, as I've often seen network drivers cause these problems.

If not, feel free to report back to us so we can look further into the problem...

share|improve this answer
Oh, this is just SO awesome, thank you so much. I was just coming here to comment I'm out of things to try again. I'll work on this. Thank you!! – Daniel Magliola May 23 '11 at 18:34
Ok, just got a trace for a hang. You can download it from here: - Thank you SO much! – Daniel Magliola May 23 '11 at 19:36
@Daniel: Updated the answer. – Tom Wijsman May 23 '11 at 21:12
I replaced my TP-Link PCI wireless card with the built-in that comes with the mobo (which gets lower signal) and the problem is gone. Tom, I have no words to describe how much I appreciate what you did. You are absolutely awesome, thank you SO much for taking the time to diagnose this. I wish I could send you more karma (or money, or anything), you really got me out of a HUGE pain in the butt. THANK YOU!!! – Daniel Magliola May 25 '11 at 4:14

My advice is to check that the firmware for the OCZ Vertex 2 is the latest. I built a computer for a friend with that SSD and we had a lot of problems until I updated the firmware on the SSD. And I hope you are running it in AHCI mode.

share|improve this answer
Also install the Rapid Storage Drivers from Intel. – xciter May 23 '11 at 12:02
Thank you! How do I check the firware version of the disk? How do I check if it's in AHCI mode (I can't find it in Device Manager)? ALso, I'm pretty sure I have the Rapid Storage Drivers. I have an "Intel Rapid Storage Technology" app that runs on startup and sits in the systray, so i'm guessing that's that. Thanks! – Daniel Magliola May 23 '11 at 12:09
You can get the utility from the OCZ site. There are numerous others too. Go into your bios. There for SATA mode it should say AHCI instead of native or compatible. – xciter May 23 '11 at 12:11
Hmmm, ok, according to "Rapid Storage Technology", my SSD firware is v1.29. There's a download for v1.33, but the "toolbox" that they give me says "No OCZ technology drives found!"... Any ideas? I'll check the BIOS now – Daniel Magliola May 23 '11 at 12:14
Yes. In order to update the drive`s firmware, you must connect it to another computer which runs windows from another drive and run the utility from there. Bear in mind that it will wipe the drive clean when it performs the update. – xciter May 23 '11 at 12:17

Just a guess, is there a 64-bits version of Skype ? Have you tried the 32-bits version ?

I had a vaguely similar problem with 32/64 java VM.

Have you tried changing your webcam and mic ? Updating their drivers ?

Have you tried turning it off and on again ?


share|improve this answer
There doesn't seem to be a 64-bit version of Skype, I'm using the 32-bit one. I've used that in my laptop (also Win 7-64) forever and never had a problem. Changing webcam: This happened before I even had the webcam, with non-video calls. I've also used both the webcam mic and my plantronics USB wireless headset, and both make it freeze. – Daniel Magliola May 23 '11 at 11:59
Could you identify when the problem started ? – Isaac Clarke May 23 '11 at 12:29
From the first day. Now, the first thing I did was install Windows + updates + drivers + all the software I normally use, so I don't have a good way of finding conflicts (if that's what you're after) other than start from a fresh windows install, install only Skype and talk a few hours with people every day and install software one by one with the calls in between until it starts freezing... And i'm trying as hard as I can to avoid repaving, since that'll mean a lot of days of work downtime for me. – Daniel Magliola May 23 '11 at 12:34

To me this seems to revolve around graphics, in particular, hardware accelerated video, which Flash now does, and probably Skype as well (it might set up HW accelerated video even if you arent currently viewing a video stream).

Nvidia drivers would be the first thing to check, if you haven't already. Make sure they are up to date. Try booting into safe-mode (with networking), and see if the problem persists, as only minimal graphics drivers will be used in safe mode.

Ideally try and get hold of a 2nd graphics card of any sort and see if the problem still occurs if you switch them. Actually, the i7 2600 has on-chip graphics right? Try removing your existing GPU and running with the onboard intel GPU and see if the problem persists then.

share|improve this answer
Thank you for your answer. I started by looking into the video card first, because of the Flash video problems. I have the absolutely latest drivers, that's for sure. I'll try the safe mode boot and see if that changes anything,but other than that, it looks like I'll be buying a new video card. My motherboard doesn't support the integrated video in the i7, which sucks enormously, but getting a cheap video card should be easier than swapping motherboards. Thank you! – Daniel Magliola May 23 '11 at 15:25

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .