Crash followed by resolution problems

Hello,
I recently purchased a new VGA cable to replace my older faulty one which caused a lot of screen tearing. Upon installing the new cable, my screen resolution was set to 1600x1200 where it should be 1920x1080. I am using a 25 inch I-Ink LCD monitor. I was able to bump up the resolution to the appropriate level at this time, although the monitor was recognized as "generic non-pnp monitor" instead of the iF125H that it usually was. While gaming, my computer froze (it tends to do that sometimes as I don't think my case is providing sufficient cooling for the graphics card (XFX GTX260 Black Edition). However, I have never had any serious trouble with this until now. After a crash, the resolution reset to 1600x1200 and I am unable to even set the display at a higher level, and all other resolutions that are lower that I attempt to change it to results in my screen going blank with "Bad Input Range" or something like that. When I open Dawn of War 2, the menus are fully accessible but any 3D image being rendered previously has been replaced with a dark pink background and some blurry words that say "Out of vidmemory". Oblivion auto defaults my settings to medium and claims "Video hardware unrecognized", even though I uninstalled and reinstalled newer drivers just now. The game still loads however and appears to play normally. Any idea what the problem or the solution could be? I am running Windows 7 Ultimate 64bit