Как мне исправить эту ошибку Synaptic manager [дубликат]

Возможный дубликат:
Не удалось загрузить информацию о репозитории из-за отсутствия CDROM

Менеджер Synaptic выдает следующую ошибку:

Failed to fetch cdrom://Ubuntu 11.04 _Natty Narwhal_ - Release i386 
  (20110427.1)/kubuntu/dists/natty/main/binary-i386/Packages  Please use apt-cdrom to 
  make this CD-ROM recognised by APT. apt-get update cannot be used to add new CD-ROMs
Failed to fetch cdrom://Ubuntu 11.04 _Natty Narwhal_ - Release i386 
  (20110427.1)/kubuntu/dists/natty/restricted/binary-i386/Packages  Please use apt-      
  cdrom to make this CD-ROM recognised by APT. apt-get update cannot be used to add new CD-ROMs
Failed to fetch cdrom://Ubuntu 11.04 _Natty Narwhal_ - Release i386 
  (20110427.1)/xubuntu/dists/natty/main/binary-i386/Packages  Please use apt-cdrom to
  make this CD-ROM recognised by APT. apt-get update cannot be used to add new CD-ROMs
Failed to fetch cdrom://Ubuntu 11.04 _Natty Narwhal_ - Release i386 
  (20110427.1)/xubuntu/dists/natty/restricted/binary-i386/Packages  
  Please use apt-cdrom to make this CD-ROM recognised by APT. apt-get update cannot be used to add new CD-ROMs