ValidateUser Fails When Password Contains HTML

I am using the MembershipUser.ResetPassword() method. Sometimes this method resets a password to a string that contains HTML characters like:
> & Consequently, any subsequent attempts to login with this new password fails on the ValidateUser method (I'm using the SqlMembershipProvider). The account is approved and not lockedout. I have verified that the Password and PasswordSalt fields in the aspnet_Membership table match exactly what is being returned by the stored procedure: aspnet_Membership_GetPasswordWithFormat (which is what, according to my research, the ValidateUser method uses under the hood in the process of comparing the submitted password with what is stored in the database). I also confirmed that the  submitted password matches both the Password field in the aspnet_Membership table and what aspnet_Membership_GetPasswordWithFormat returns.
How can I ensure that the ResetPassword( ...