You need to remove the problem entry from your boot.ini file.

See if this helps.
Go to Start -> Run and enter msconfig in the Open box.
Click OK.
Note: If you don't have run on your Start menu hitting the
Windows + R keys will launch the Run box.
In the System Configuration Utility, click on the Boot.ini tab.
On the Boot.ini page, hit the "Check all boot paths".
You should be able to delete the entry for XP setup.
Click OK and restart your computer.

If that doesn't fix the problem, take a look at the information
in this article.

How to edit the Boot.ini file in Windows XP
http://support.microsoft.com/kb/q289022/

You can also go to Control Panel and double click the System
icon.
In System properties, click on the Advanced tab.
On the Advanced page, hit the Setting button in the Startup and
Recovery section.
In Startup and Recovery, change the entry in the box under
"Default operating system" from XP setup to your working XP
installation.
Change the entry next to "Time to display operating systems" to
0.
Click OK twice and restart your computer.

Good luck

Nepatsfan