I've posted this to the Fedora distro forum with no responses, maybe I'll have better luck here.

I'm having a very frustrating problem with my Fedora box. Basically it will lock up periodically, but only when in a desktop environment such as gnome or kde. I can play RtCW for hours with no lockups at all.

Info:
Fedora Core 1 (kernel 2.4.22-1.2166)
P4 2.4c HT
Asus P4P800 D
MSI nvidia Ti4200 128 meg vid card
1 gig matched corsair ram

running dual displays as two separate X displays

When it started:
All was working perfectly for months, and I don't remember making any changes, but one day it just started to crash. I very well may have installed or updated something a few days prior and just did not experience the crash right away. Again - I stress - for months it was working perfectly.

Details:
Computer locks up when using any desktop GUI. It can happen any time I am doing any window manipulation (could be OK all night and then happen), but I can make it happen right away if I open a bunch of windows in my left (primary) display and start closing them.

It will not happen if I am playing a game in full screen mode no matter how long I play for. Also, I can have many videos playing at the same time, be running CPUburn and moving large chunks of data from my drive into ram and back to the drive again - as long as I don't manipulate any of the windows, it will work flawlessly.

I doubt it is ram, because I never have file corruption, I can make it happen from a fresh boot with little ram in use, and the computer functions normally even when the ram is 100% in use as long as I don't manipulate any windows.

It never locks up in Windows 2000 (but I really don't like windows, so it is very depressing having to use it)

What I have tried since it started:
Tried three different kernels (all 2.4.22, but different builds) Tried different versions of the Nvidia driver (currently using the most recent 5xxx version, but the 4xxx version was causing the problem as well)

Updated all packages that had updates.

Looked over all logs (all logs look fine - they look as if the computer was just hard-reset suddenly. No report of errors around the time of lock up. I have checked out the XFree logs before X starts to make sure I could see them too)

Updated my BIOS

Nothing I have tried has changed anything at all.

Any ideas? Any information I could supply that would help?

Gnome or KDE? or both? or other?
Which versions of each?

It happens in both. I think I've got KDE 3.1.x and gnome is 2.5.x (I'll have to come back and supply more accurate version numbers when I get home. Don't have the machine with me.) I just installed core 1 and then kept updating it with apt periodocally - so whatever is current for core 1. I'll post back when I have solid information for you though.

It solidly locks the whole computer - no ssh, no response to ping, nothing. Before this it was so solid that I assumed it was a hardware failure for my first week of trying to fix it.

I had the same problem. It was faulty ram.
run memtest86 and check all your ram.

Just to add: The Linux ram utilization is different than windows. Windows most of the time will not crash due to bad ram. Sounds like you are accessing deeper cells when opening a new shell which spawns a new process.

Thanks for the advice - I'll give that a try. Hadn't actually tried memtest yet because I don't have a floppy drive, but I'll find a cd image somewhere I'm sure.

I'm not convinced this will be the problem though, as it happens when I close windows far more than when I open them. I can't remember it happening specifically on the opening of a new window at all. Also, I can play video games for hours with no issues, under linux or windows.

None the less, ram problems can be strange, so it is worth a shot for sure.