If you want the mythtv user to login automatically, you can do it calling this application:
In GDM Setup, on the Security tab, check the box Enable Automatic Login and select the mythtv user from the pull down menu. Then click on close.
If the user mythtv is not in the pull down menu, go to the tab Users and highlight mythtv in the Exclude section and the use the green arrow to transfer it to the Include section. Then go back to the Security tab and the user mythtv should be there.
