Hey all... I'm having an interesting issue. It appears my users from BEFORE the upgrade are having trouble accessing the community. New users - no problem. Is this an issue caused by something common that I've overlooked? The site is http://kiaforteforum.com/
Well, if you can submit a ticket and provide login details of a user with problems, we can look into it. Some of the errors reported there shouldn't have anything to do with old accounts except for lacking permissions (which always need to be checked after an import). The member list comment is a little confusing as there's nothing that lists members by registration date out of the box.
However, in the screenshots, there's an issue loading the CSS -- it's possible there are browser add-ons incorrectly manipulating it or something between your server and them that's preventing it from working. Without being able to reproduce it (and I don't expect I would), it's not something we could make any recommendations about.