I keep getting CTD's (Crash To Desktop) when I enter a new area. I have the original 4 CD version of PS:T with full install. I am on vista 64 and installed it to my desktop to bypass the UAC and the security issues that occur in the regular programs folder.
I had the same problem with the original, 4 CD version of the game and copying the CD contents onto my hard drive didn't help either. I ended up buying the 2CD version, it's really, really cheap now.