Ric, do you turn you cofuser off for extended periods time? If so that can causse the system to release its IP address. Then when you restart it has to aquire a new IP. The site keeps you logged in by IP, so if it changes you must reenter your info.
Just one thought on what might be causing it. I am sure there are others.
Well I do turn it off a couple of times a day. Maybe you are on the right track. I wonder if its dumping its cookies when it turns off... I did that in college a lot...