Back up your PS3, rebuild the data base.
There is a lot more to it, but essentially it would be like a "clean Install of say Windows 7 on your PC"
Sometimes files get corrupted, this is just a way to freshen everything up.
There are video's on how to do this or go to the PlayStation EU Forums and post in the technical help section, usually a MOD will get back to you within 24 hours. Or people from the PlayStation Community that have had this problem will have step by step guides on how to fix your problem once clarified. These fixes are sanctioned by PlayStation.
If all else fails PM a PlayStation Mod - Pretoria for example.