Random X crashes, Corrupted Framebuffer. bad times.

[mushroom blue]

okay, so this has been a problem for quite a while now, but I've never found a way to fix it.

I'm using the Nvidia drivers, and X tends to randomly crash during times of heavy load. it used to be much worse, where every time I'd start an SDL application (Zsnes, RTCW:ET, Frozen Bubble, etc), X would change resolutions, and the computer would hang with a black screen with nothing but my mouse icon (can't ssh in or anything). I found that disabling the kernel 2.4's drm and agpgart fixed that problem rather well (or at least I'm not able to replicate it so far).

only things I generally have running are Gnome 2.4, Xchat, Gaim, Mozilla Firebird, and sometimes bittorrent. nothing really taxing. however, I'll start to notice X getting a little sluggish once in a while while surfing, and then X will die. and when X dies, it seems to corrupt the framebuffer along with it. after GDM restarts, I'll try to drop to console, and I'll get a strip of pink-ish scrambled text at the top of my screen that tries to display the tty. however, nothing seems to work at the terminal when I try to run anything (I've tried everything from top to an emerge of kdelibs), and I usually just SysRq my way to a reboot. and the only thing I can glean from XFree86 logs are it terminated with signal 11

don't think it's a heat issue, because I installed a shiny new LARGE heatsink a few months ago (which stopped a problem with kernel panics I was having). I can rule out the AGPGART and drm, because they're not being used.

so, help?