Membership Premium causing Events Calendar to give 'error 404'

I upgraded to Membership and it has created havoc on my live site
I also at the time upgraded to events calendar ( to 3.9.1 from 3.7.1.
I have now been able to stabilize by a full system restore -- however I cannot run or the previous membership without it blocking my event calendar entries
Even if membership is active but disabled --- it creates 404 errors. ONly a full uninstall/delete can I get my events to appear.

Therefore, I cannot accept orders as it requires a user to create a free account.

While the site is visible via live no ability register is causing loss of customers to register for my events and I have to move and protect my premium content. See the problems on my cloned site

I enabled wpmu support access.

thanks- desperate for help.