Membership Premium causing Events Calendar to give 'error 404'

I upgraded to Membership 3.5.2.9 and it has created havoc on my live site
https://premium.wpmudev.org/forums/topic/membership-causing-chaos-on-my-live-site#post-858193
I also at the time upgraded to events calendar (tri.be) to 3.9.1 from 3.7.1.
I have now been able to stabilize by a full system restore -- however I cannot run 3.5.2.9 or the previous membership 3.5.1.8 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 develeopment4.p....series.com site

I enabled wpmu support access.

thanks- desperate for help.

mike