Booting a USB hard drive

[Peter Bonucci <peter.bonucci@verizon.net>]

I have installed Debian onto a USB hard drive and would like to boot to the 
disk and run Debian.

When I try to boot directly to this disk, my laptop tries to perform a network 
boot.  This normal for this laptop when it can't find the boot device.

The laptop uses the grub2 bootloader.  When I boot the laptop and put grub 
into the command mode, "ls" does not list the USB drive.

How can I run Debian from this disk?  I could use a boot CD, but it looks like 
grub doesn't see the drive.

Any suggestions?

Thanks, 

Peter