Lowercase login issues

We had a flux of member sign ups and during the sign up process, i got contacted several times due to users having trouble registering for our site due to this lower case only error during sign up? I've lost over 50 sign ups :slight_frown:. http://tradeslive.com/socialnetwork/ I'd like to simplify my sign up with only email and user name, and the other fields are filled out from the user profile.