Windows 2000 restarts 5 times

We are running Win 2000 SP2 with Novell client for NT/2000 and NDS authentication. When we load something like Viruscan software or PCAnywhere and restart the system, the system will come up almost to the login screen and then restart itself. Thiswill occur usually 5 times before the login screen appears and we can continue to login and operate normally. Any explanation on why this happens and can it be avoided? Thanks