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My Windows 7 PC is blocking quite often for a couple of seconds up to half a minute or so. I tried to find the problem with the process monitor by filtering all system calls that take over 2 seconds and find that these always have the following stacktrace segment:

0   fltmgr.sys  FltAcquirePushLockShared
1   fltmgr.sys  FltIsCallbackDataDirty
2   fltmgr.sys  fltmgr.sys

The next frame is NtCreateFile in most cases. The calls take often 2-10 seconds, but sometimes up to 50 seconds on a nearly idle system. The HDD (actually, a solid state disc) does not seem to be the problem - HD Tune shows no problems in the benchmark and the error scan, and Process Explorer also gives no hint of unusual CPU or IO activity. And I am pretty certain it is not a virus or something. :-)

How can I find out the actual problem? Are there any helpful tools?

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Use xperf from the WPT (part of the Windows 8 SDK) to trace disk IO:

Run the script, minimize the CMD Window and when you have the issue again, go back to the cmd, wait 15-20s, press a key to stop logging. Open it with xperfview and look in the Disk IO graph which processes causes the high disk IO.

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The annoying thing is: there is no high IO or CPU activity. I checked that with process explorer. (I extended the question a little to make that clear.) So that probably would not help, would it? – hstoerr Nov 26 '12 at 20:21
try it out and look if it helps or not. – magicandre1981 Nov 26 '12 at 20:59

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