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This just started today: after my WinVista computer has been idle for a few hours (with nothing running) the disk usage light goes on and the HD starts to 'whistle'. While this is going on the computer is extremely slow, almost to the point of hanging (it takes 10-15 seconds to open the Start menu)

My question is:

  1. Why does this happen? I have had this happen to my Win95 once or twice, but never within a few months of each other; before, a cold boot had fixed it but this has happened twice in the same day so far

  2. Is this merely annoying, or would it damage the HD?

  3. Can I do anything to prevent it from happening again?

EDIT: @James was right, the disk is about to fail. When I restarted it just now, I got a message from the BIOS saying "Hard disk failure is imminent!" and the Intel Matrix Console says that "A hard disk in the system is reporting that it is about to fail". Time to look for a new HD...

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Vista does have known issues on some hardware where the search index tool goes crazy on the disk every so often. You might want to investigate that. As for damaging the hard drive, any access on a drive will shorten its lifespan, but that's practically impossible to quantify. – user3463 Nov 23 '11 at 6:43
up vote 2 down vote accepted

On one hand, the fact that you say the drive is making a 'whistling' noise and the computer is so unresponsive makes me think that the drive could be dying. But because you have stated that it only happens when the computer is idle, it seems that it could be a scheduled task set to run at a certain time or when the computer is not in use. Are you sure your virus scanner is not doing doing scheduled scans when it happens?

Next time it happens, I suggest you try to open the Task Manager to see if you can spot a process that is using a lot of CPU time and accessing the disk. Be sure to click the Show processes from all users button. Also try to find out if there is a pattern to when it occurs, e.g. does it occur almost exactly two hours after you last used the computer.

It would be useful to know if the activity stops shortly after you press a key or move the mouse. If so then it further suggests that a scheduled task is set to run only when the computer is idle. There are a few programs set to run like this, e.g. the Windows performance monitoring tool, but none I can think of that run that regularly. It is possible to view scheduled tasks using Start -> Run -> taskschd.msc. The program gives a list of tasks that have run recently, but finding the relevant one may not be easy.

Whilst it could be that search indexing is causing this, it does not normally cause a problem as it is designed to run in the background without harming performance significantly. The simplest way to rule out the indexing service is to temporarily disable it.

If you're still having the same symptoms it could be a problem with the drive itself. I suggest you download SpeedFan and check the S.M.A.R.T data for errors. There are also some tests in the program that you can run manually. It could also be useful to run chkdsk (accessible by right-clicking the drive in My Computer and clicking the Tools tab, then Check now...) as you may have some bad sectors. In the mean time, be sure to have a backup of all your important data.

Lastly if you still have no leads then I wonder if malware could cause this. Specifically, a rootkit that's up to no good and able to hide its activity in Windows. What kind of malware protection do you have?

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It doesn't stop after pressing a key/moving the mouse. The computer isn't connected to the internet, so I have ClamWin antivirus. Scans are scheduled for 2AM so I don't think it's that. – Nate Koppenhaver Nov 23 '11 at 16:49
Have you opened any files lately that could contain a virus? As I understand, ClamAV doesn't have a real-time scanner by default which means that a rootkit would go straight past it. – James Nov 23 '11 at 17:10
If it happens again see if you can find out if any processes are showing an unusual amount of activity. – James Nov 23 '11 at 17:12
CHKDSK says the drive is good. ("0 KB in bad sectors"). It hasn't happened again yet, but when it does I'll check which processes are active – Nate Koppenhaver Nov 23 '11 at 23:57
Did you try SpeedFan in the end? I think it would be worth doing as the S.M.A.R.T data is the drive's own diagnostic system and should be the best indicator of whether it is failing. SpeedFan would also be useful for checking whether the drive is overheating which is a possibility. – James Nov 24 '11 at 11:01

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