perldoc -q 500 (aka "My CGI script runs from the command  line but not
+ the browser.  (500 Server Error)")
[download]

will tell you a lot about what you want to know.

perldoc -q messages (aka "How can I get better error messages from a C
+GI program?")
[download]

will tell you even more.

--
Regards,
Helgi Briem
helgi DOT briem AT decode DOT is