I've been having a problem with a few discs lately (Dude, Where's My Car? and Remember the Titans, in particular) where about an hour in I start to get pixelation - its definately not all movies, I watched Goldeneye and probably 10-15 other discs with no problem recently. Eventually the pixelation gets too bad and player sort of "gives up" and stays locked, I have to go back to menu to resume player. I removed the disc for Dude, Where's My Car, cleaned it off the point I can see nothing on the disc, and I have plenty of ventilation for the player (fan blowing into it from the back, its raised so there are a few inches of free space on top and under it). Any ideas?

Thanks,
-Jeff