Back in February I added a second hard drive to my desktop since my primary hard drive was pretty quickly filling up, and I started moving a lot of things over from my C drive to the new hard drive, including a lot of games, since those were taking up the bulk of the space. So I wholesale dumped a lot of folders - Guild Wars, Guild Wars 2, iTunes, etc. including my Steam folders onto the new hard drive and didn't think much of it at the time.
Fast forward to now, and I've started noticing some issues with certain Steam games when I try to run them. I'll run them and the program will go into full screen for a moment while it loads and then cut out with a "suchandsuch.exe has suddenly stopped working" error message. This has only happened with my Steam games that I had before I installed the new hard drive, but not with all of them (i.e. Portal works just fine, but Thief: The Dark Project doesn't, both of which I've had for ages). I'm not sure why moving hard drives would affect some games but not others, but I can't think of anything else specific that might have started causing problems.
Any thoughts on fixes or should I suck it up and start reinstalling the games that don't work?