The graphical interface did not properly start, which is needed for graphical logins. It is likely that the X Window System or GDM is not properly configured.
Methodd y rhyngwyneb graffigol gychwyn, ac mae angen hwn er mwyn mewngofnodi'n raffigol. Mae'n debyg nad yw System Ffenestri X neu GDM wedi ei gyflunio'n gywir.