Thanks for the quick replies.
CLONNEN - Yes, I've been the MSCONFIG route already.
silverous - Have now downloaded Bootvis and shall report on next boot.
PsiFox - H/D defragged, disk cleaned up and spyware also run.
I have a feeling it may be to do with my new external USB Creative Sound Card (I unplugged it yesterday and thought it was just a coincidence that the pc behaved perfectly this morning. Just plugged the soundcard back in, the pc froze and on re-boot, I had the same probs with app start-up. So, off to the Creative site for new drivers!)