12.10 64 bit running on Toshiba Satellite C870-198 with single user account.

I understand that the Ubuntu philosophy is to have the root account disabled, the administrative user account password being
used with 'sudo' to carry out administrative tasks. I have done nothing to enable the root account, and have not set a root
password.

If I launch the Samba configuration GUI from the Dash launcher it requests the administrative password, but rejects my login
password, which is accepted by 'gksudo system-config-samba'.

Similarly my login password is rejected by another GUI tool, System Testing, which explicitly requests the root password.

Are these failures due to bugs in the distribution, or is there something wrong with my installation?

Thanks,

Kevin