In addition to jfroebe's comment, I also recommend three basic pieces of debugging advice:

• I'd change our $db1 = DBI->connect( $url, $user, $password ) or die "Failure!\n"; to be explicit about failures with our $db1 = DBI->connect( $url, $user, $password, {RaiseError => 1} ) or die "Failure!\n";*,
• use CGI::Carp qw(fatalsToBrowser); to have the browser show you what Perl thinks of the crashes.
• Trigger tracing with DBI via something like DBI->trace(1, 'dbi.log');, to show you details of the transactions.

I know it sounds like a great deal of work, but it can make a huge difference in how you debug your code. And in how much we can help you. :)

* As I recall, some DBD modules have it on by default, others off. Better safe than sorry.