krileon wrote: It's possible you've done something to cause user rows to no longer be in sync... Best approach is to pretty much disable everything 1 by 1 to see if it resolves.

I have to admit that I moved the last 3-4 users via DB tables. But it went really smooth, IMHO. I took care about the J! users table & the comprofiler table. I also ran CB tools and checks... which added the nessecary ACL info... I guess, this is not the problem and a reliable way to do a minor usersync (right?).

As far as I remember, this action had no bad influence on the site.

Disabling:
Yes. Thats what i am doing right now. Turn anything OFF, except for the minimal login and display funcionality.

I will also do some upgrades on the older website copy, just to be sure if and when the issue re-occurs.