crashing pda??:S

[theBIGone]

ok here's the problem.. every once in a while, my pda just crashes.. i wouldn't mind that much if it didn't happen every week... but unfortunately it kinda does. my rom version is 4.01.12 and radio version 4.21.00. i really don't have a clue of how to upgrade the radioversion. .. so that's why

Any id for how the crash is fixed???

tnx
joost