xp sp2 download, computer won't boot up now

I have downloaded xp sp2 overnight, and this morning it
asked me to restart the computer as sp2 download was
complete and the installation was in process and the
computer needed to be restarted to complete the
installation.
When I restart the computer it freezes shortly after
start up with Windows XP on screen.
If I start the computer in safe mode with networking
either on or off, The computer freezes with a heap of
sentences showing, with the last one reading the
following-
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS\System 32
\Drivers\Mup.sys
If I try to restart using 'Last known good configuration'
it still freezes on the XP page with the black background.
What am I to do know?