I'm still really lost on this issue. I've been exchanging notes with one the lead developers of the software that powers this board, and he can't figure it out either. I really think it has to be a user issue, probably with IE. (Just found a huge display issue caused by Norton.) I can't control what happens once the code leaves the server, but I keep hoping I can figure out a fix - hard when I can't even identify the problem. It doesn't seem to be cookies. It doesn't seem to be php sessions. I just don't know.
Going to try a couple more things today, but it's not looking good.
For those still having trouble. Do you have firewalls, internet security, etc.? What versions of IE do you have? (you can check under 'Help > About Internet Explorer')