Users complaining they cannot update email notific

My users want to receive email notifications when they receive a PM but they cannot update their settings in the profile to allow this. If you click the Yes button and then click update, it says it is updated but the no radio button is check when you go backand look into the profile page.

I suspect register.asp. Can anyone tell me what is wrong?

Also, is it possible for an administrator to change the setting on a member's email notification? I can't seem to do it as admin.