I am sure that I did as I checked the file again by downloading it. It is defiantely your CMS file. I uploaded it again, and reloaded FC and same issue.
It does put the extra info on the URL (#=hex #)
http://www.DOMAIN.com/forum/member.p...##############
If I go to the address bar and press enter, it does redirect properly (but then it isn't a POST any more)
I am not sure if this would be part of the issue, but I do have "Mod Rewrite Friendly URLs" set on the site.