Help! Major Membership plugin issue.

I have have a major issue with the membership plugin. When I install the plugin the 'Pages' tab on the administration side stops working. The sub menu item 'Add New' works, but not the 'Pages' sub menu item, and thus the page listings of the website doesn't load and instead I get a 404 error after a about 4 minutes!

Can anyone help me with this membership plugin that supposedly work perfectly with MU 3.1.3?