Not sure if this helps but I have had trouble in the past with my McAfee antivirus not like the ACE component. Usually it won't allow the ACE to run at all and I have not seen it yet with ACE but it has removed the add-on manager entirely and I have to take the trouble to fix it.
This has most recently occurred after I downloaded the latest 757 fix. I had disable every feature of the McAfee program but after that ACE worked for me.
Hope there is help in there somewhere
Good luck.
Warren