When trying to sign up, I had to type really slow when entering my email address. When I typed at normal speed, the sign-up window's email-field dropped about 4 out of 6 letters. All the other fields seemed to work normally. (True for repeated tries with Firefox 3.6, after rebooting/restarting both FF and computer) (Chrome worked fine, but FF is my main browser and I wanted this site in my History).
If this an intentional deterrent against bots, that's actually a great idea! But you need to tell people that, AND let them type at normal non-bot speed. It was very frustrating.
If, however, this is a bug with your sign-up thing, I hope you don't have too much trouble fixing it. Or it's a weird thing that only happened to me, I'm sorry for ranting.