How to Fix Ps3 Freezing?

I've had a ps3 slim for a while now, and it has frozen on a game twice already, does anyone know what causes it and if there's any way to fix it
I haven't read the problems in the manual so if it says anything there please tell me
Thanks

Suggestion:

yeah and if you listen to blackevil or whatever your house will be on fire because of the RRoD make sure your ps3 isn't played too long and dust is kept out of the vents and you'll be fine