When I try to sign up I get the message "Profile addresses must be alphanumeric" and it won't let me sign up

This usually happens when you are trying to enter something into the "User Name" field that has special characters in it like @ - $ _ % # etc. You can only enter a user name that has numbers and letters and no spaces. So for example, instead of bj@hotspot or bj hotspot, you'll need to enter bjhotspot.