This is a problem (or feature) with clipboard monitoring in the main program. It looks through the clipboard for "http://" and splits each instance into a link. These links are then matched against each plugin to see whether they are supported. Your example link is split into "http ://adf.ly/500607" and "http ://www.mediafire.com/?mxxxxxxxxxxxxxx", both of which are supported by plugins.
We will see what we can do about it. For now, you can disable clipboard monitoring for the adf.ly plugin in Options > Preferences > Plugins.