Game's wont start!

Hello,

I had my ps3 on Regero 4.30 CFW.

I didn't really like it... So I went through the downgrading back 3.55 process...

Then I went to 3.55 Kmeaw CFW.

I did ALL that so I could mod games online...

When I went to put on Gran Turismo 5, it wouldn't start, it would say Corrupt data and then some code... I also tried Black ops (NOT BLACK OPS 2) and same thing happened...

Also my computer is being EXTREMELY slow and that's like throwing gas on a fire because I'm gradually getting pissed by every minute -_-.

I've spent almost 3 hours trying to figure this out... And I got NOTHING. Please help?

And as of right now, I'm creating a back up of Black ops. Apparently I have 29GB left on HDD and Black ops is 18.177GB... I'm guessing GT5 is around twice that...

A noob friendly tutorial would be nice...