OK, I know people have been whining about this all around the web, but I just want to be sure it's not something more than a software issue.

First off, this only happens in Oblivion. It either
A) crashes completely (the monitor loses it's signal, so I guess the graphics card is shut or something),

B) Hangs up, with the monitor still recieving a signal, albeit still a black nothingness, or

C) I somehow manage to get back to desktop without crashing (happened only once).

At first, the game would work fine for an hour or so before crashing. I wasn't overly bothered by it, but still tried out some of the "fixes" on the elderscrolls forums - which only made things worse. I eventually decided to reformat my drive and reinstall windows. I put in the latest drivers for my system, all in the correct order, updated windows, installed directx 9.0c march 2006 version, dotNET 1.1 and 2.0 etc. Only now, I can barely open my quest log before the f&#%er crashes my comp. again. I've tried different drivers for my graphics card, 6.1, 6.2 and 6.3, both vanilla and Omega versions. Neither make any difference.
I've tried disabling all overclocking and tweaks in the bios, and running the graphics card unoverclocked, with various settings, but to avail. This whole mess is just..wierd. I can't figure it out. I've got two friends who play this as well, one of them has an Asus x550 128 mb card with 512 megs of ram and a A64 Venice 3000+, and it runs fine, albeit somewhat laggy. The other guy's got an X2 4400+ with a gig of ram and an geforce 7800gtx 256, and it runs flawlessly. If this actually is an issue with the game itself I'd be surprised, although the only other explanation would be that my X800 is defective in some way.