Not sure what's up, but if I click on the User CP etc along the top or just try to get back to the top of B3D Forum, it just logs me out. Same thing happens if I try to access PM's from "Your Notifications".
hm... weird. Seems my FF21 is just acting strange in general. :s Youtube links don't go where I click (nothing happens). I did try out waterfox recently then removed it... wonder if that borked it.
Did you delete all B3D cookies from FF options before going the reinstall route? If not, try that first next time. Seems to solve things when vBulletin suddenly decides to go all screwy once in a while.
Yeah, tried that (I also don't check the "remember me" box for that particular computer). Something funky was going on besides cookie this time I think. I was getting strange behaviour on Youtube even without logging in, and other sites were having trouble loading avatars/thumbnails.