It has come to our attention that part of the problem is actually a misconfiguration of the server. I have asked the server admin to fix the problem, but have gotten no response.
It seems that when you go to the downloads, or other sections, you are being redirected by the server to the actual server name of "web.amiga.org" which breaks the session variable if not the cookie as well.
There is nothing we can currently do except ask that you log into web.amiga.org (when you find yourself redirected there) as well to see if that alleviates the problem. Hopefully there will be a resolution coming shortly.