Thanks for the quick reply.
Isn't this the support forum for 2.5? Or are you saying you don't support older versions at all anymore?
I can't upgrade to the newest version because my server doesn't support it.
Turning on debug (as described in the documentation link you provided) didn't show any errors other than:
Strict Standards: Declaration of JCacheControllerPage::store() should be compatible with JCacheController::store($data, $id, $group = NULL) in /libraries/joomla/cache/controller/page.php on line 199
and the pop-up window for the scan.php still remained blank.