Trouble with Comodo Anti Virus



Hi. I want to remove Comodo Anti Virus, and try the Nod32 free trail, but I can't remove Comodo at all. When I try, there is always some part of it left behind and it messes up my notebook to a point that I have to use system restore to get back to normal. I have tried several times and nothing seems to work.
I sent Comodo an email and all they tell me to do is to go to "add and remove" and follow the instructions. Wow, great help!
So I'm hoping that someone might know a way to do this. Any help would be greatly appreciated.
Thanks.

Wayne
XP,SP2
.