Did you by any chance just check for lotteries on the other forum name and not change it back? Also make sure that you aren't inadvertently blocking some cookies that the forum uses. Those are the only things I can think of offhand that would be on your end to cause this. Otherwise, yeah, sounds like a bug on the forum side.
One other thing, which may or may not have anything to do with this. How are you accessing the forum when this happens? Desktop/laptop, mobile device, pad? Do you access the forums from more than one device? Also what browser (version) are you using? Just thinking it may be specific to a device/browser, and looking for a way to help narrow it down.
"Everyone's got one. Better to be a smart one than a dumb one." - me
"It's people like you that [I]think[/I] you know everything that give those of us that [I]do[/I] a bad name." - me
"Eat, drink, and be Merry, 'cause Pippin was a fool of a Took."