Checking your MantisBT installation...
PHP
There is a performance issue on windows for PHP versions < 5.4 in openssl_random_pseudo_bytes
For best performance upgrade to PHP > 5.4.0. WARN
Maybe there is more than one PHP version installed on your system.
One for CLI (Command Line) and another one which is used by your web server.
To see the version, create a file test.php with the following content in the root directory of your Mantis installation and run the script in your browser
OMG. How did that happen? I installed php via the WebPI plugin within the IIS 8.5 management console. This means it fubar'd the php install (thanks microsoft!) and now I'm stumped. Do I uninstall php completely and then manually install the one specific version? Or do I attempt to figure out where it put the 5.3 version and manually update just that to 5.6? Bleh. Thanks for the clue that showed me what's happening at any rate.