Just three more questions, your honor...

The script executes with perl checkvars.cgi, but does it execute with just ./checkvars.cgi?
Also, are you on a Linux/Unix server?
Are you coding on the server or coding remotely and transfering the file?

"Of course, your honor, I am leading the witness." If the above answers are No, Yes, and remotely (with Win32), then read on, you might be running into a ^M problem. If not, then ignore the following.

If you've transfered the files from Win32 to Linux/Unix via FTP, there is a chance that the extra ^M used on Win32 as a line seperator followed your files over. You can test this by opening your file in VI's binary mode (vi -b file or vim -b file). If you see ^M at the end of each line, that is the problem. The magic #! can not find /usr/bin/perl^M. The main reason I'm suggesting this as the problem is that a friend at work recently had the same symptoms and a binary FTP was the culpret. Try sending the file again via FTP in ascii mode (just type ascii at the FTP prompt). Or within VI (or VIM) type :%s/^M//g To type the ^M, type <Ctl>VM.

Cheers!
Casey