Well, thanks everyone for all the tips........My machine has been up and running for close on 24 hrs now without a hiccup so it looks like that CD was the cause of the headache.........Doh.....I feel so stoooooopid. Thing is, I've been running cd's in macs from the early days with system 7,8 9 and now 10. Until now of course, every time you rebooted, the CD used to pop out on startup and everything would be hunky dory. This doesn't happen in X of course and I suppose that's why it was so easily overlooked and ignored. The first, I am sure, of many basic OSX mistakes I will make!! I am still trying to get my head round files apparently scattered all over the place. I'm sure OS9 wasn't really any easier but somehow, Applications, Documents, Extensions and Control Panels in 9 (and earlier) seemed so much easier to understand. Whatever happened to the computer for the rest of us!! Time to sign up to an OSX group I suppose.....any recommendations as to the best one? (Particularly for simpleton newbies like me!!)