Sorry, I can't replicate this issue, all I can do is make suggestions based on some previous posts.
Your error message should also be displayed in the Windows Event Log and may be more detailed:
From the Control Panel->Administrative Tools->Event Viewer->Application
Follow the instructions in this topic
to download the Microsoft Visual C++ 2005 Redistributable Package (x86) which may help.
This post has another MS fix for MySQLviewtopic.php?f=16&t=32617
Also try adding Win32DisableAcceptEx
to the end of your httpd.conf file - has been known to fix some strange issues but usually only for Apache.
Sometimes other programs like the Firefox browser use port 3306 and fail to release it when finished with it.
Check using xampp-portcheck.exe
if that port is free - if it is being used by another program then close that program and wait up to 5 minutes or so for the system to close that port then try to stop MySQL after starting first it in your XCP.
There may be other responses to your issue that may give more details, but for now it would seem to be your XP that may be at fault especially after reinstalling XAMPP.
BTW does Apache start OK and can you get to the Welcome Page at http://localhost
and do the demos work?