Error 500 (trying to edit user profile)

[Phoenix Voyage]

We have a user in our forum who has been unable to register successfully. He gets a message stating his email doesn't exist in the system, but his username is. When I try to edit his profile, I receive a java enabler error (500). Because of a lot of personally identifiable information, I'm not posting the error code here. But I'll send it upon request.

Please help!

Caused by: java.lang.NullPointerException