I still have not resolved this issue with my limited Linux experience. I have tested now three times with a fresh install, the results are as follows:

Fresh install, no cheat codes, no additional drivers: Screen image deteriorates after a while (variable) and machine has to be rebooted.
Fresh install, no cheat codes, appropriate nVidia drivers installed: Machine freezes after a short while and has to be rebooted.
Fresh install, no3d cheat code: running fine, uptime several hours now.

The no3d code is what Klaus suggested previously, I tried it after I'd already had some issues with the same install and it didn't work out. It seems to work fine when used with a fresh install.