Are there any pro's on Norton Anti-Virus who can venture a guess as to why this is happening?

My scan started as per normal about a week ago. Half way through everything shut down. Everything. It took about 2 hours to get back on the net. Norton refused to open. I uninstalled and re-installed it. It now indicates that my scan was interrupted and that I should click to resume. Nothing happens when I click. Nothing happens when I click to scan via the normal route either.

I changed the auto-run to a current time and watched and waited. Nothing happened.

So while Norton is enabled, I don't seem to be getting any protection. I am also concerned that virus scans are not running. (Manual or otherwise)

Any suggestions?

(All live updates etc have been installed)