Question : mup.sys

My windows XP in safe mode gets to mup.sys then it will get no further.  I don't have the installation cd

Answer : mup.sys

Here is a link that contains several causes and solutions to mups.sys errors during boot up. You didn't give too many details, so I hope this helps.

http://www.aitechsolutions.net/mupdotsysXPhang.html

TK