No aparace gestor inicio sesion

[desna]

Hola  Distro ubuntu 12.04 (bugtraq)
El gestor inicio sesion no aparece para logearme
Desaparece rapido el inicio del plymouth y da esta salida:

sbin/ plymouth: symbol lookup error: sbin/ plymouth : undefined symbol: ply character device exists could not read byte from child: success
bin/ plymouth: symbol lookup error: bin/ plymouth: undefined symbol: ply command parser add command alias
scanning for btrfs filesystem
bin/ plymouth: symbol lookup error: bin/ plymouth: undefined symbol: ply command parser add command alias

Saludos