I recently acquired Battlestar Galactica blu-ray complete collection and happily sat down to watch the mini-series. When I put in the next disc to begin watching series one the blu-ray player philips bdp5100/12 made a bit of a juddering noise a couple of times, and I could hear it try to spin the disc but failing.

Then an message saying "unknown disc" appeared. I tried every disc and some worked fine, others had the same problem.

I took the blu-ray boxset back and exchanged, but had the same problem.

I'm trying to work out what the issue is and how to fix it.

I've downloaded the most recent firmware, but that didn't help.

I'm going to buy a lens cleaner - although I find it strange that some discs work and some don't.

I'm hoping someone else has encountered a similar problem and found a way to fix it.