PS3 reads some...but not all

[Bigblue622]

Hey guys, my little brothers PS3 started acting weird last night. We took it from our house to our dads and hooked it up to a SD TV from his LCD and of course we reset the video settings and the XMB is running fine.

He played COD:WAW, Condemned 2 and Timeshift last night fine. However he wanted to watch a movie and we tried several DVD's and BD's and none of them worked. I tried turning off various options in video settings such as the upscaler and others and nothing worked.

This morning, he comes downstairs and tells me the games won't work, so I go up there and sure enough nothing. I took some compressed air and cleaned out some dust b/c it's well over a year old. Timeshift then worked as did COD WAW but not Condemned.

5 minutes ago I tried Condemned again and this time it worked and he's playing it now, I still don't know about BD's but this morning they still didn't work.

So what can cause some disks to play and others not? I have no other ideas, it worked fine for BD's earlier this week and he's never had a issue with it at all.