I'm wondering if this is a mod issue. I used zero mods, and consequently have had zero game-breaking bugs.

I've had a few minor hiccups here and there, but nothing that kept me from finishing the game twice. Running Windows 7...

I've played through the game three times, once vanilla (apart from the Widescreen Mod) and twice with every mod (the latest on each occasion, so slightly different versions), and never encountered any bugs on any playthrough as far as I remember.