I've mentioned in the past that I've had some nasty performance problems with Windows Vista, particularly with the machine hanging at times paging so extreme that it completely freezes. Several weeks ago I completely disabled the pagefile and a few other things, and that helped for a while. It didn't remove the problem completely, but now it happened far more infrequently and freezed the machine for shorter periods of time.

This week, however, it happened several times, and I started looking a bit more closely as to what the issue is. I noticed this time it was a bit more reproducible and usually happened when I opened up "Windows Fax And Scan", an application that really shouldn't cause much trouble and that I had noticed before sometimes triggered the issue.

After digging a bit deeper, I think I found the culprit! I have a Microsoft Lifecam VX-6000. It's a simple webcam that does the trick for what little I use it, and my needs are pretty modest to begin with. I always thought the software was a little clunky, but since I rarely used it much, I didn't mind.

However, today, after the machine froze for about 10 minutes paging (remember, with no pagefile!)  I noticed that a process, started by MSCAMS32.EXE, which corresponds to the MSCamSvc service. It usually doesn't seem to use much memory, but seems to page a lot. How much? This time it was to the tune of 64'000.000+ pagefaults. Yes, 64 million pagefaults (and I hadn't even used the cam recently). The closest process in paging was dwm.exe with around 19 million.

And that's when I realized what the deal with Windows Fax and Scan was: The MS software/driver makes the webcam available to WIA (Windows Image Acquisition), which might be what WFaS uses to interact with scanner!

For now I've simply disabled the offending service, and we'll see how it goes. Nasty stuff...

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Tomas Restrepo

Software developer located in Colombia.