Can't read disk after being on for a little while?

Okay, so, what happens with my Playstation 3, is that after I turn it on, if I put a disc in immediately, or already have on in, it'll read and play it just fine. However, after that, if I change discs, or if I have it on for a little, it won't read any discs that I insert until I shut it off for a while. Is there anything I can do to fix this? It's model number is CHECHK01, if that helps at all. Updated to latest system update, and it's in an area where it's fans aren't blocked.