I actually don't think you will find an answer to this one...
It wouldn't be Norton stopping you from running the two programs together, it's a matter of limewire and the game you are playing being just to much for the computer to cope with...
Do you ever experience any lag in your games when you have to many other windows open ??...
I know when WoW is being run on my computer and I want to check my inbox, it will take ages for my emails to load...
My suggestion would be to run each app at different times...
