i get them occasionally, drive kinda like "ticks" - then eventually dashboard comes up saying disc can't be read. It only ever happens on PGR3 disc, not on condemned/King Kong. Maybe they were cheapo discs that they used for PGR3 and we seem to get the odd duffer? If it was a drive fault i would have thought it would do it with all dics.
I'll keep an eye on it anyway and see how it goes