Norton is a bit better in my professional opinion.
But all virus software have their pros and cons.
Every computer is differnt... 3rd party software might be affecting your copy, or possibly a older install of another virus software. Also are you sure your not already infected?
How long has it been since you had a clean install. A computer that is a few years old and have had programs downloaded/installed/removed makes the whole system less stable.
Computer trouble can be a pain.... I'm just happy it pays well