Unfortunately this can happen when you use tweaking utilities, even when it comes to software provided by large companies such as Norton/Symantec. I don't know anything about that particular program, so I can only offer three suggestions:

1.) Repost in the Computer Help forum and see if anyone else has experience with this program.

2.) Click here for XQDC Software's support site, and try e-mailing them at support@x-setup.net to see what the author can suggest.

3.) Perform a repair installation of Windows XP to repair the damage.

Good luck!