CGI Perl upload script 500 internal server error

[misson]

Yes, there are three things in the error log:
[Tue Apr 06 08:58:14 2010] [error] [client 68.41.93.111] File does not exist: /home/USERNAME/public_html/500.shtml
[Tue Apr 06 08:58:13 2010] [error] [client 68.41.93.111] File does not exist: /home/USERNAME/public_html/favicon.ico
[Tue Apr 06 08:58:10 2010] [error] [client 68.41.93.111] File does not exist: /home/USERNAME/public_html/favicon.ico

Those are safe to ignore. The first means you haven't created a custom error page for the 500 status response, and the latter two mean you haven't created a site icon.

I'm a newbie to web coding, so I have no idea what a BOM is or what a shebang line is... (is it the line that tells the script where perl is installed?)

Note the links in my post:

Check that there's not a BOM messing up the shebang line.

Read my sig and follow the directions for information on what a BOM and shebang are. (Note: the shebang link has been updated. It originally pointed to a thread on common problems causing the error you were getting.)