it should normally be... #! /path/to/perl

this tells the system where to find perl, whether it's in your path or not. but windows should use the PATH environment variable... so make sure it's in your path in windows (which can sometimes be weird) if you're using windows.

but if you're using apache for some CGI or whatever, then i believe that you can use just use: #! perl so maybe apache isn't setup correctly if you're going that route.