Is this a tremulous only problem?.. how is the temp in your case.. i've seen that type of thing when the card overheats..
Yes its a tremulous only problem... The only thing I've ever seen that had even remotely the same problem was with Doom 3 - which used the same blue launching window. But doom 3 would crash during that window with an OpenGL error. Just getting a patch fixed that, though.
Try installing the latest drivers, not just the same ones as your friend - also the latest Windows updates. If that doesn't work start disabling graphics options until the game looks normal... that's all i can suggest 
I have the latest drivers, beta drivers too. They don't seem to fix it though. Tried disabling the graphics options offered by the Nvidia CP but no luck there either. Can't adjust in game options due to obvious reasons...
Send me your hacks.
I figured a video couldn't be
photoshop'd (See post #5) but apparently that yields no support from some members here too.
Thanks to everyone else who tried to help, though. Seemed like a fun game but I'd rather just take some shrooms and go play Super Mario 64 with a dusty cartridge.