error 21 with Linux Ubuntu 8.04 1

i installed Ubuntu 8.04 on my usb enclosed hard drive. so now i have a dual boot with windows xp/Ubuntu 8.041. now i was able to use Ubuntu 8.041 after it was done installing but after i shut down the computer and boot back up again i get
Grub loading stage 1.5

Grub loading please wait.....
Error 21

how can i fix this problem?

 

Error 21 means "Can not find disk"

Is it plugged in?

 

yes its plugged in.

 

can your hardware boot from usb? is grub configured properly? usb will be /dev/sda1-2-3-4-5-6 depending...

 

i am new to this whole linux thing so you if you don't mind can you tell me how i would go about grub configured properly? thanks

 

https://help.ubuntu.com/community/GrubHowto

It relates to ubuntu.. look at the ubuntu wiki and forums first before asking.. like me they love saying RTFM

 

ok thanks will look at the link.

 

You might need to assign a UUID and replace the /dev/sdxx entry in grub with that. USB devices can change their nodes unpredictably, but UUIDs or drive labels don't. There should be loads of info on how to do that out there.

 

ok thanks. i will look into that.