How to clone Virtualbox disk images (VDI)

Please follow the steps below

1. Open VirtualBox
2. Click on the Virtual Machine you want to clone
3. Now click File>Virtual Media Manager 
4. When the Virtual Machine Manager appears, click on the .vdi file that you want to clone and then click Release – this will release the .vdi from the VM. THIS IS IMPORTANT. If you miss this step you will encounter UUID conflicts. 
5. Fire up command prompt (Start>Run>cmd [enter])
6. Enter the following command:

< File path of VBoxManage> clonehd “” “”

For me this command was:

kernel panic not syncing virtualbox !!!!!!!!!!!!

When i was tried to start up a new virtual Linux machine with downloaded VDI from virtualbox's site,
I got the same error "kernel panic not syncing virtualbox "


Solution is very Simple.....

Go to the Oracle VM VirtualBox Manager, right-click your CentOs Machine and click on "Settings".
Go to Storage -> Right-click the vdi in SATA Controller and click on "Remove attachment.
Go to the IDE Controller and click on Add Hard Disk
Retrieve your vdi file from your hard drive and boot your CentOS machine