Bloody computers...

Oh thats just great, as soon as I buy PS CS2 and install it it going wrong. Double click on a file on an external drive and PS takes ages to load in and then says:
There is a serious error. Reinstall Photoshop

Tried that and immediately, Installation was not successful...
Restarted the MacBook Pro and hey presto! all is fine now.

Bloody Computers! Grrr....