Could already be infected with the blaster or nachi worm - very typical when
connecting an unpatched pc to the Internet. First, disconnect from the
Internet, your pc will just continue to spread the worm to others until you
do this. Get SP4 and Blaster patch onto a cdrom from anther pc that isn't
infected and install them, and scan with anti-virus software. You can also
get the blaster removal tool from various sites including Microsoft's.
If it's not the worm, then suggest looking up specific error in the
knowledge base.