I think it really means that NIS crashed during installation, or at least caused msmin to crash.
Welcome to the whacky world of NIS.
Does your OE still work?
Is NIS still working, or did it not manage to complete it's install?
Do the Symantec help forums give you any clues?
Have a read here click here
Try disabling or not installing Norton Anti-Spam
Try something better than NIS