Background: My computer is running Windows 7 Ultimate 64-bit. The CPU is AMD Phenom II X4 955. The motherboard is ASUS M5A88-M. About a month ago, there was a power outage at my place, and power flickered on and off a few times before coming on for good.
The problem: Since then, my computer has displayed strange intermittent freezing behavior. When I started up after the power outage, there were no freezes for 3 days. It then froze repeatedly over the course of the next week, then didn't freeze for about two weeks, then froze again, then didn't freeze for another few days, and then froze again.
I've noticed these common elements:
The freezes almost always occur either soon after booting up, or after leaving the computer idle for a long time (8+ hours). If it boots up and doesn't freeze within the first few minutes, it will work all day with no problems or even sluggishness, and sometimes (as I mentioned above) it will continue to work for days or weeks before freezing again.
When a freeze occurs, CPU usage seems to drop to zero. This was surprising to me and makes me think it is not a problem with some software grabbing too many resources.
The freeze appears to affect apps one by one when I try to do something. Often the taskbar will freeze, but I can still use alt-tab to switch between apps. Some apps will be unresponsive and can't be switched to, but others will work. Usually if I try to "do something" in a given app (e.g., click a menu, select an item in a list), it will freeze. Eventually all apps freeze this way. I then will often still be able to move windows, but eventually they will leave "trails" as the screen fails to repaint properly.
Sometimes if I wait awhile (anywhere from 5 to 30 minutes), the computer will "wake up" and function semi-normally for a few minutes before lapsing back into unresponsiveness.
What I've tried:
I tried these things:
I ran SMART diagnostics on the hard drive using SpeedFan and SeaTools. I also ran a "long generic" test using SeaTools. No errors were found and all SMART stats come up OK.
I ran the Windows Memory Diagnostic tool and it found no errors. I ran Memtest86 overnight; it made three passes and found no errors.
I ran scans with Microsoft Security Essentials as well as MalwareBytes and they found no major threats (just a couple registry tracker entries).
I ran SFC /SCANNOW. It reported no system file problems.
I booted a Linux live CD and hung around for awhile and experienced no problems, but I'm not sure this means much because the problem is intermittent even on Windows, so it could just be that I lucked out.
I noticed an "unknown device" in device manager which I figured out was an ACPI device. I installed drivers for it. I thought maybe some power settings had gotten messed up, so I tried disabling stuff in BIOS and in Windows power management settings (e.g., disabling AMD Cool 'n' Quiet, disabling CPU throttling in Windows, etc.). At times I thought I had fixed it but it would still freeze the next day. (I also blew a bunch of dust off the CPU in case it was overheating.)
I've also poked around in the Windows Event Viewer. During the middle of the night on the nights when it froze (i.e., before I noticed the freeze in the morning), there are sporadic timeout errors for certain Windows services (usually the Windows Error Reporting service). This suggests it is actually freezing sometimes in the night and Windows services are timing out.
These timeout errors are sporadic. It looks like most clumps of such errors are preceded by this event (which is not an error, just an "Information" message):
Microsoft Antimalware Real-time Protection has restarted a feature. It is recommended that you run a full system scan to detect any items that may have been missed while this agent was down.
Feature: On Access
Reason: The filter driver has restarted scanning items and is out of pass through mode.
I'm not sure if this means the problem really lies with something Microsoft Security Essentials is doing, or if it's just the canary in the mine that's the first thing to indicate the freeze is beginning. But if the computer boots up without freezing, I can run MSE scans manually with no problems (and it finds no threats).
I've also been using SpeedFan to log stuff like the CPU temps and voltages, because I wondered if there were any patterns there. I haven't found anything unusual in the readings themselves, but there are sporadic gaps in the logs. I set SpeedFan to log every 3 seconds, but, during the night on those same nights where a freeze occurred, there are many places where log entries have gaps of about 5 minutes. These gaps ONLY appear to occur at these problematic times (i.e., in the middle of the night when it is freezing or going to freeze in the morning). It again suggests it's freezing up in the middle of the night to such an extent that SpeedFan can't continue its logging.
The question:
What is going on? The fact that these problems seemed to begin after a power failure makes me suspect hardware problems, but I don't know what hardware could be causing it. On the other hand, the fact that the crashes always appear to happen at certain times (after long idle or on boot) make me suspicious that it's connected to some software thing like MSE updating itself.
The event viewer timeouts and SpeedFan log gaps all point to a freeze that starts happening after I go to bed and continues intermittently until morning (when I reboot). But I can't find any information about what is actually happening that could be causing the freezes. The only errors I can find in event viewer are just "Timeout error I am frozen" things that don't indicate any actual error condition; they just seem to mean the freeze has already taken place.
The hard disk and memory diagnostics seem to rule out those components. My current hardware guesses are the motherboard, the CPU, or the power supply. Do the problems I described above sound like something that could be caused by those components? Alternatively, are there other software solutions I should try?
