I don't know the internals as well as Captain DJ and Zog do (and they've been taking a well-deserved break after getting this place into shape), but something in here might be of use:
http://digitalcomicmuseum.com/forum/index.php/topic,1810.0.htmlIf the site says you're not logged in (I don't think I've seen that before), that could be bad data somewhere. Best bet would be to log out of the site, clear your web browser's cookies, maybe restart the browser just to make sure there's nothing lingering, then log back in and try again.
Before you do that, though, be sure to check the videos linked in the FAQ above, to make sure you registered and logged in correctly. I've been dealing with computers longer than I care to admit, and every once in a while, I still overlook little details like that. (I also spent an hour yelling at some tech support guy, once, because he asked if my cable box was plugged in. Of course I...oh, hey, it looks like the plug slipped out. Oops.)