Cannot backup using Windows Vista

[Ganz Doof]

I am trying to back-up my laptop (running Vista Business) on to an external
Hard Disk (500gb). I chose the Windows Complete Backup option and the system
verifies my external disk, starts to run and almost instantly gives me an
error message "Back Up Failed. Not all volumes containing system data are
included in the backup (0x80780018)

Any suggestions on what I should do?

 

[Nonny]

If you wish to clone your drive,
it's best to use a 3rd party utility

Windows Complete Backup makes an image.