This error occurs when the perl modules "GD" and "GD::Graph" have not been installed on your server.

You have two options if you receive this error message: Either contact your web hosting provider and request that they install the GD and GD::Graph Perl Modules on your server, or deactivate the graphing feature by opening Password Protector SD's admin.pl file in a text editor such as notepad, scroll to line 9846 (you can also search for "use GD::") and replace these lines:

use GD::Graph::bars;
use GD::Graph::pie;
use GD::Graph::lines;

With the following:

# use GD::Graph::bars;
# use GD::Graph::pie;
# use GD::Graph::lines;