When someone tries to register with OpenID verification, the field for "Reason for joining" disappears along with the password entries.
I couldn't find any button or link for submitting a new bug report to Mantis; sorry for posting this here in support.
Regular users can't submit bugs to Mantis. This is done so we can verify that it's a bug first and ensure that the problem is described well. The password fields are supposed to disappear for OpenID, but custom fields aren't. I will look into this more when I get home from work in about an hour or so.
Reason for joining is a mod, I think so I think you should ask the mod's author...
Ah, didn't even remember that -- sorry.
I just checked the install file, this is definitely an issue with the mod itself. Sorry for bothering you with it.