Sorry for the trouble! Typically this happens because of a poor internet connection at signup. Because many exhibit halls have poor internet connections, this is often an issue for those who sign up at a convention.
But there's a simple fix!
If you're on Chrome Browser:
Hit CMD-SHIFT-R (Mac) or CTRL-SHIFT-R (PC) to cache refresh your browser.
The problem should go away permanently.
If you're on any other browser:
Clear your cache and refresh the page or perform a "cache refresh."
The problem should go away permanently.
If you have any other problems with this, we'd be happy to help you via live chat. Just shoot us a quick message and we typically respond within a few minutes.