I hacked and downgraded then installed a custom firmware on my friends PSP. After a few days he came back saying it freezes up randomly anywhere. He gave it back and I tried to look for the problem. I changed CPU Speed, Kernel, Plain Modules in UMD, original flash0, everything. What I found out that was different was that his was a TA-82. Does this have anything to do with the instability? The PSP is really unstable, as I can't even play a game without it freezing.
EDIT: I tried 3.80M33-5 and 3.90M33-3, both freeze randomly.