Can't save Samba settings after updating to 9.3.

[cgimusic]

Hi, I appear to be unable to make any changes to the Samba/CIFS settings from the web interface after installing 9.3. For the "Guest account" field I get the error "The user *username* is not valid." with *username* being replaced with whatever the username in the field is. I have tried with the nobody, daemon and root local accounts and also with some of my LDAP accounts but neither seem to work. Does anyone have any idea what's going on?