The forum sofwtare works fine. If you find that it's not working then this is usually due to incorrect setup.
Things that can prevent the forum from working are sofwtare like, abti-virus, firewall, internet security, etc. that can prevent ASP pages from executing correctly.
Also IE has problems with cookies, it could be that the cookie cach on your machine is corrupted (clearout all internet files and cookies cache), also if the way your site is connected differs from the norm (IP masking, domain forwarding, ect.) this does course browsers particully IE to have problems reading back in the cookie correctly. You could try using a browser like Mozilla to see if that works, if so then you know it is an IE cookie issue with the way your site is connected to.