PSP turning off

[carlins_leap]

Hi all,

First of all let me apologise for any stupid questions I may ask - I'm very new to this!

I bought a PSP a few years ago and thought it was lost or stolen - but i've found it again - it was packed in a box!!!

Anyway its one with the 1.5 version firmware and has fastloader 0.7 on it.
The memory stick came fully loaded for me, so I haven't done anything with it at all.
The is a folder on there called ISO and has ISO files for 2 games that work fine.
I put some other ISO's on there but I'm having mixed results.
One that I put on there worked fine - but the rest I can see in my games menu, but when I press X - the screen freezes, before the PSP eventually just goes off.

Any suggestions?

As I say i'm really new to this and really don't have a clue what to try next - any tips would be really appreciated!

Thanks in advance
Steve