Question: I'm on a Eee PC and I am running Windows XP and Ubuntu 10.04. I'm starting a big project tomorrow and I wanted to cleanly reinstall both operating systems. After entering the pre-install Windows environement, I let my system run as per usual, however, after I returned to my desk I found a blank screen with `error: no such partition` and a GRUB rescue command prompt. After digging around a bit online I found `ls` which returns `(hd0) (hd0,4) (hd0,3) (hd0,2) (hd0,1)` and `set` which returns `prefix=(hd0,5)/boot/grub && root=hd0,5`

I have Ubuntu on a flash drive, but I can't get that to work because every time I boot up it goes straight to the error screen.

Answer: 
I had this same problem, and I only managed to fix it by installing the OS I wanted to use onto a different drive. I believe the problem was cause by the drive grub thought contained the OS to boot only being accessible after any given OS had fully booted (I don't know why, it wasn't my computer, but the drive seemed to be some sort of add-on SSD drive).

To get back to the way everything was before, you're going to have to find a way to boot into Windows and use the [mbrfix program](http://www.sysint.no/nedlasting/mbrfix.htm) or boot into Windows recovery and use the built in fixmbr command (confusing, I know).

Sorry this couldn't be more specific, but I don't know what your exact problem is.
well,what OS do you want..?
well if you want xp,then follow all these guidelines... :)

\*first,boot your windows xp recovery disc.
\*then press R to go to recovery console.
\*then type these codes:

fixboot
fixmbr
then type EXIT to restart your pc.now the xp bootloader appears..! :)