I am trying to understand an application hang problem that started up lately on my windows xp system. The system runs fine for days (sometimes) without ever shutting down or putting it to sleep, but the problem first shows up as one of the apps hanging. The application's UI stops responding or one or more background threads hang, so even though the GUI is responding, it is not doing anything (e.g., in VirtualDub's case, the UI responds fine, but the job doesn't progress and I won't even be able to abort it).

The weirdness part comes from the fact that if I try to kill such an app, the program that is used to kill it goes into the same mode (i.e, that hangs instead of the original). E.g., if I use Process Explorer to kill it, the original program exits, but procexp now hangs. If I use another instance of procexp to kill the one that is hanging, this repeats, so there is always at least one program hanging in that state. This is not specific to procexp, I tried the native task manager and even the "End Process" dialog from windows explorer that shows up when you try to close a non-responsive GUI (in this case, the explorer itself hangs). The only program that didn't hang after the kill, is the command line taskkill. However, in this case, explorer hangs instead of taskkill.

Also, once this problem starts manifesting, it soon ends up freezing the whole system to the extent that even a clean shutdown is not possible, so I have learned to reboot as soon as I notice this problem, however this is very inconvenient, as I often have encoding batch jobs going on which can't continue the job after the restart. The longer I leave the system running after seeing this problem, the more applications get into this state.

I have tried to do a repair install but that didn't make any difference. I also uninstalled some of the newer installs, but again no difference. I tried to search online, but got inundating results for generic hang and crash related problems.

Though I couldn't notice any pattern, it seems as though the problem is more frequent if I have some video encoding going on at that time. I had the system running for days when I only do browsing and internet audio/video chat before I decide to start encoding something and the problem starts to show up. I am not too sure if it is the encoding program that first hangs, though I almost always noticed that too hanging (like the VirtualDub stopping to make progress). I also had to reboot 3 times on one day when I was heavily experimenting with encoding. I would appreciate any help in narrowing down this problem and save me the trouble of reinstalling. I don't especially want to loose my gotd installs.