A lil' PS3 help

[BStecke]

So here's the deal. I went to watch 300 the other day, a disc I've watched at least three or four times since I've owned it. Last time I watched it it was fine. As I get about 15 minutes into the film, the disc would freeze for a couple seconds and then skip ahead a few seconds and continue playing. I check the disc for scratches, dirt, etc. Nothin'. The disc went from the player when I watched it last, when it played perfectly fine, to the case where it has sat since.

Second, I go to watch Drillbit Taylor, another disc I've watched a couple times since purchasing it. Same deal, about an hour in it would freeze for a few seconds, then skip ahead and continue playing. No scratches, no dirt.

In both cases, it seems like it's almost a defect in the disc, as both of them occur in the same exact place every time.

I took the PS3 completely apart and got all the dust out of it. Put it back together, try these discs again, same problem.

Here's the mind f***. Every other disc plays fine. I've watched four or five discs, Blu-ray and DVD, over the last few days with absolutely no problem. Yet, 300 and Drillbit both continue to do the same thing at the exact same point in the film. Again, I've watched both a few times so it's not a production problem, the discs are clean and scratch free, and the console is about as clean as humanly possible for being almost two years old. I'm almost going back to the rumors of disc rot from the format war days, because I honestly can't think of any reason why these two discs decided they didn't like my PS3 all of a sudden.

Any ideas?