I'm not quite sure where this really belongs, but I don't think the backwaters of Help are the right place so I'm putting it into Home/General Discussion.
Apologies for not spotting this earlier; it should get picked up now. Unfortunately it's not one I can answer but someone here should be able to help.
Edit : If you're running Norton and McAfee at the same time that might well cause problems. I take it Norton is inactive? But still installed?