Sometimes you just have to cut your losses and move on! Yesterday I spent a while trying to work out why Norton 360 wouldn't work on a PC (not mine - I was trying to fix it remotely using LogMeIn). The software refused to run a virus scan and wouldn't run in Auto Protect mode, which after all is the whole point of virus software. I tried uninstalling using the Norton Removal Tool to ensure it was properly removed and then reinstalling, with no success.
In the end I dumped Norton 360, installed my favourite security software - F-Secure Internet Security 2008 and all was well. F-Secure offers a 30 day free trial at the moment.
Score - F-Secure 1, Norton 0