Usually that error is generated when you failed to follow the install instructions for the addon in particular the running 2 times of the setup_xampp.bat
which sets up the conf files correctly for your installation of XAMPP.
The installation is simple and the instruction can be found here:
http://www.apachefriends.org/winxampp/r ... n-perl.txt
ENGLISH: Simply extract this add-on in your current XAMPP folder.
All older files are overwritten.
Then start the "setup_xampp.bat" to configure XAMPP with Perl.
Now restart apache.
After that start the "setup_xampp.bat" file again , you can choose "with mod_perl" or "without mod_perl".
Just install again, over your first attempt, follow the above instructions (no need to uninstall anything) and all should be fine again.