It happened to me about 4 or 5 times and it occured after i typed in my username on the first level/2002. i was typing in the username "darkquest" and the first time i typed it in differently, as "DarkQuest", it worked. maybe its just coincidence. Basically, after i typed in my username and name, it wouldnt let me go off that that page, it didnt freeze but if i tried to press the ok button, it would come up with an "are you sure?" message and even if i clicked yes, it would automatically cancel my action. I hope this helps!

Weird, I didn't have any issues but I typed my username in with lowercase, only my name in with a capital letter

I just joined to play games an' stuff, so I may seem like an idiot, makin' an account a few seconds ago. But on the first level, I typed in my user, and then it completely cashed. Then I did it lowercase, and it was okay for the rest of the time.