I installed Ubuntu 9.10 on an external usb drive yesterday, with Windows XP on the primary drive. I forgot that Ubuntu decides by default to write grub to the primary drive in this situation, overwriting the Windows MBR. Ergh! Why doesn't Ubuntu warn about that first?!
In addition to overwriting the Windows MBR, this grub setup also won't boot anything without the external usb drive connected.
I wanted to simply put back the XP MBR, but in this case I don't have the XP Administrator password, so I couldn't boot into the Recovery Console. Why does XP only offer this method for fixing the MBR?!
Ubuntu and Windows are annoying me today.
Fortunately I do have a local admin account on Windows, so I was able to use the third-party mbrfix.exe to rewrite the MBR. Again, why doesn't Windows include such a utility? *sigh*