While working in another plugin that uses custom post types I get the error:
Fatal error: Call to undefined function get_current_screen() in /usr/local/pem/vhosts/112327/webspace/siteapps/24990/htdocs/wp-content/plugins/mint-sliders/mintfunc.php on line 118
The other plugin is bbPress and I don't think the problem is there. In fact, I don't see why bbpress would be calling a function in your plugin. Does it have something to do with you declaring functions globally?
Any help you can give me is appreciated.