new users get ERROR: Connection dropped... when logging into webmail

This is one of those "things used to work and all of a sudden they don't anymore" situations...

As of late, when I create new users, at least for new virtual hosts, they get "ERROR: Connection dropped by IMAP server.
Query: CAPABILITY"

Can you give me a clue as to what I might need to reset and where?

TIA!

Status: 
Closed (fixed)