If your Blu-ray Discs aren't playing properly in your PlayStation 3, then the answer may be as simple as a dirty lens in the Blu-ray Disc drive. Anybody with a few screwdrivers can do this themselves, right at home, no repair costs. But it would void your PS3 warranty, so beware.
This video tutorial will show you the exact process of cleaning your PS3's Blu-ray drive lens. See the disassembly of the actual Blu-ray player, bit by bit, piece by piece, until you have reached the actual lens. Cleaning is a simple as using a cotton swab.