Thanks Mark, Ill try what you suggest by looking at the security settings as I regularly have a clear out of unwanted junk.

I doubt if SP2 is anything to do with it as I checked back on this thread and I first reported it on 2nd Oct so it was running OK before then and Ive had no problems with SP2 either in installation or running programs.

I also have a hunch that it may be the .jpeg security update thats responsible because it was about then that it happened.