Try deleting your save for that game as it maybe corrupted, or just hope they push thru. I've had it once where LBP locked up when it said it was writing to the HD, had do hard reset it, then it didn't load. Some people with that issue said they had to erase the save to fix it, but luckily it worked for me on the 2nd attempt.
Focker I'd repeat what other said, try using a decent vacuum on the ducts even. If not try to open it up and run it if the warranty is void and you're comforable with electronics like that.