Can’t Open the Virtualbox in my Ubuntu

Hi Everyone,
As a newbie of Ubuntu 8.10 had bad day in opening the VirtualBox 2.1.4 after installing Windows 7 on it. After a successful installation of Windows 7 and followed the appropriate settings of VirtualBox for Windows 7 then have restart Ubuntu. When trying to open VirtualBox it gave me unnecessary error message. Could anyone give an advice of these?
Thank you techyv.

Error message:
VirtualBox – Error
Failed to start the virtual machine Kubuntu.
VirtualBox can’t operate in VMX root mode. Please disable the
KVM kernel extension. Recompile your kernel and reboot
(VERR_VMX_IN_VMX_ROOT_MODE)
