Security :: PasswordRecovery Not Completing Security Answer Verification?

I'm using asp.net's built-in membership provider with security question-and-answer enabled for password recovery against a SQL Server 2005 db. For some users, this works fine and they're able to receive their passwords. For others, and it's not clear what separates the two groups, the security answer is never properly processed. It doesn't matter if the answer is correct or incorrect, the page merely reloads without confirming or denying the request.As for events, VerifyingAnswer is being triggered, but not AnswerLookupError (if answer is incorrect) or SendingMail (if answer is correct). I ran a SQL trace during one instance, and the aspnet_Membership_GetUserByName stored procedure is being called, but nothing else gets called after. I would expect that aspnet_Membership_GetPassword would be called, which passes the security answer as a parameter, but it isn't.