My apps won't open on 2.2, then again on 3.0

I recently got a new ipod touch (after having one before, friend broke it accidentally), I was annoyed to find that any apps I downloaded didn't open

They worked for a couple of days after I bought it, then when I tapped the app, I saw a frozen screen for a second or two, then it returned to the home screen

@ the time I thought that upgrading to 3.0 (as it came with 2.2) would solve the problem, new software and that

but it only made the problem worse, the frozen screen now only flashes on screen then it returns immediately back the home screen

I have hard reset it numerous times
I have plugged it into the computer and synced it numerous times
and I don't really want to restore it as it is a hassle

can anyone help me please