I have never had, and it is very rare case I hear it from people.
Forum software is up-to-date. I do the maintenance rather often, and no error reports, beyond people just trying to log in with incorrect passwords all the time.
However, knowing vast variety of browsers, computer systems, connection types, cookie settings, etc, I'm sure free forum software that's rather old (compared to swiftly changing nature of equipment), is bound to have some glitches once in a while with someone.
There have been odd changes, such as system how new members are being approved. Old one was much better, but the new system often results that people get approved roughly once a week when I remember to do it.
