[Plugin: Custom Content Type Manager] PHP Version Required?

Absolutely, moving hosts could cause the issue: PHP 5.2 is required. The syntax of the older PHP versions is not the same, nor are the object oriented calls possible. PHP 4 is dead; WP itself will require PHP 5 starting with 3.2 I think. The plugin does check for a minimum required PHP version when the plugin is loaded, but simply due to the constructs used in the tests themselves, the tests may fail if attempted on an older PHP (as in your case).

I’d recommend a different server.