Shaun, I had a problem like this a few years ago. My AutoCad was being removed by nortons. I had to change the anti virus software. After many problems I was instructed to download the Nortons removal tool, it seems that using the add remove programs from the control panel leaves many norton programs running on your workstation.
I would recomend that you try this.
http://www.softpedia.com/get/Tweak/U...val-Tool.shtml
It may help.