Edit: Just tried creating a new account and I could use @ in the username and password and email field. So I dont know why you cant do so as well.
Also I bleieve you can use your forum account's username and password to log in to impulse.
I take it your trying to use @ in your username? Or are cant you type it in the email field?
If your trying to use @ in your user name and it does not work its because its not a supported character. Youll have to not use @ in youre username.
