MacBook :: Open Up Photo Booth It's Just Black, And The Green Light Won't Come On?

I've been having a strange issue with my iSight recently. It will work sometimes, and then one day for no reason, it won't. When I open up photo booth it's just black, and the green light won't come on. When I try and video chat, it says the camera is in use, which it obviously isn't. It will let me chat, though, the other person just can't see me. If I restart my computer, the camera will start working again, but the same issue will come back within a few days. About a month ago I called Applecare about this and a palmrest crack, and sent it in. Since I had to turn it off to send it in, though, they didn't see any problem when they received it and thus didn't do anything about it. Once the issue came back again, I took it to an Apple store (about an hour away) so I could show someone in person. The genius sent it in for me and they replaced several parts, but it's happening again! This is very frustrating, and I really don't want to have to make the drive again. My school store sells Macs and I might be able to take it there for them to have a look. I've had a few other issues with this machine, too, do you think they might just consider a replacement at this point? I've had a couple other small issues with the machine in the past (DOA battery, palmrest cracks, stuck pixels).

It's a late '07 Blackbook with plenty of Applecare left. Also, the issue started after (but not right after) I installed Snow Leopard, if that might have anything to do with anything.