Ultimate Facebook conflicting with Affiliate plugin

Whenever my Ultimate Facebook and Affiliate plugins are active together with another two plugins (I haven’t determined which ones yet) the whole wp-admin area returns a 500 server error

Server error

The website encountered an error while retrieving http://www.faceliftupvc.com/test/wp-admin/plugins.php?activate=true&plugin_status=all&paged=1&s=. It may be down for maintenance or configured incorrectly.

Here are some suggestions:

Reload this webpage later.

HTTP Error 500 (Internal Server Error): An unexpected condition was encountered while the server was attempting to fulfill the request.

These two plugins work fine on their own, with no other plugins activated and as well with just the two of them active at once with all others inactive. I’ve tested them having one other plugin active at a time, and done that for all of them in the list and they still work fine.

big screenshot on evernote

So is there a known conflict between Ultimate Facbook, Affiliate and two or more plugins