Have you had Tingalf approach you in a cut scene yet? If not, try running the configuration program and switching to software mode, and perhaps lower the game resolution. That helps with some cut scene problems.
If you start a new game, can you run to Ars Magicana and approach Geoff without crashing? If you save the new game, you could use
iZakaroN's SaveEditor (or from
Kiya's site, with description) to boost the character's constitution (at least) before heading to Ars Magicana.
This would help determine if the problem is with the game itself, or something in the save game folder (ie a corrupt file).
Troubleshooting Tips (& manual install procedure)