Gender field causes error to registering members when enabled

I noticed that when the Gender field in the profile information is enabled, someone who registers a new account gets a MySQL error. The new account DOES get created, but the user wouldn't know at first glance because you don't get the action successful message or anything, just a blank page with the error code.

So I've had to disable the field for now since I don't want users to either try and register 15 accounts because they have no idea the first attempt actually worked - not anymore than I want members not coming back after signing up because they figured there was a problem with the site working properly.

Anyone been able to fix this?

Bug thread: https://efiction.org/forums/index.php?topic=5603.0