I moved from VB4 to Xenforo some days ago. Now there are some users with thousand posts came to me about their problem to accessing to the forum. the system shows them an error like this "user 'XXX could not be found.". They posts have showed with their usernames but as a guest, also I checked the user table on database but they weren't there, it seems they are all gone. actually there is a common symptom among them, all of them had exclamation sign ( !) in their usernames.
What is the solution? I find some add-on, but they are all useless in my case.