virtualization: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/lib/plainbox-providers-1/checkbox/bin/virtualization - from package: plainbox-provider-checkbox

You may install the required package with command apt-get install {package}

Error in other languages:
virtualization: bevel nie gevind nie
virtualization: comandă negăsită
virtualization: comando não encontrado
virtualization: commande introuvable
virtualization: command not found
virtualization: käsku ei ole
virtualization: không tìm thấy lệnh
virtualization: komanda nerasta
virtualization: Kommando nicht gefunden.
virtualization: kommandot finns inte
virtualization: komut yok
virtualization: nie znaleziono polecenia
virtualization: níor aimsíodh an t-ordú
virtualization: no se encontró la orden
virtualization: no s'ha trobat l'ordre
virtualization: opdracht niet gevonden
virtualization: parancs nem található
virtualization: perintah tidak ditemukan
virtualization: príkaz nenájdený
virtualization: příkaz nenalezen
virtualization: команда не найдена
virtualization: командата не е открита
virtualization: 命令找不到
virtualization: コマンドが見つかりません