If there is any chance that you will want to run this using mod_perl, it is important to change those declarations to:

use vars qw (
  $q $sess_id $usr_name $password
);
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I tried to explain why at RE (3): BrainPain-Help, don't think I succeeded. If someone wants to give me feedback on how to improve that description, I would appreciate it....

EDIT
Note that the mod_perl issue is likely to be an issue with other "fast CGI" type approaches like FastCGI and ASP. The underlying problem is not Apache/mod_perl, it is with how Perl names things.