The same thing happened to me a while ago. I found out that it had to do with the psp thinking the umd door was open (if held the door closed kind of hard it wouldn't happen). It stopped when i took my psp apart and put it back together. I think was because my psp casing was loose. Maybe try...
Pepsi, and it's companies, did not pull out of Russia like most did, even tho they orig said they would, so I boycott them. (Except when drunk at 2am and Taco bell is only place open.)