So, I was given a PSP 1001 from a friend that had 5.0 m33-6 installed on it, as well as a 4gb memory stick pro duo. He thought it was useless since the PSP seemed to have a problem with the L trigger and thought it was always held down. I managed to fix it by unmounting the trigger, cleaning it, and remounting it, and now the L trigger works fine. However, whenever I play one of my friend's backups, I find that if I play for more than about five minutes and attempt to save, the game seems to hang. The music continues as if nothing happened, and some of the games idle animations continue to play, but the controls freeze up and I'm unable to do anything (Including turn off the power), so it forces me to take the battery out to turn the system off. This happens on just about every backup I try to play. At first, I thought it might be a problem with the firmware, so I tried to reflash m33-6, but nothing changed, so I tried to switch to 5.50 GEN-D3, but nothing changed then, either. I've attempted to format the memory stick a few times, but that didn't work. Any other ideas as to what the problem may be and how to fix it?

Side Note: If I try to save after JUST starting the game up, it works fine. It just won't save after I clear a single stage of a game.