NS on Windows XP: 100% CPU load, program does not load

I installed Norton Security under Windows XP SP3 (32bit) in an Virtual PC. Installation went fine, but after rebooting I do not see NS. But in the taskmanager I see NS.exe with 100% CPU load, and this continues for hours.

When I manually start NS via the startmenu, I see an AutoFix window after some time. But this also takes forever with no solution.

I rebooted the VPC several times now. What can I do? Reinstall NS?