Remove & reistall tool

I am receiving the "at risk" message every few days. I run the quick scan and it scans to 2939 items and doesn't finish the scan, even after an hour. I then use the remove & reinstall tool. It removes but doesn't reinstall. It tells me I have no product even though my subscription is active.

The first time I had the "live chat" person install it for me. The next couple of times I was able to go to the manager section and install myself.

I have 2 questions : Why am I "at risk" so often and why does the RnR tool not reinstall my product. I have 2 computers and this only happens on 1 of them. Using NIS, XP and Firefox.