Anti-virus

I recently purchased Norton SystemWorks 2001,after installing and rebooting i got a blue screen with a Windows Protection Error. The problem is the “symevnt.386” file, I downloaded their latest file “sevinst.exe” but i am having the same problem. Mycomputer is 550Mhz with 256 megs of ram. My OS is Windows ME. I have also tried McAfee anti-virus and i had the same problem.Do i have to uninstall my Wins 98SE files?