I have installed Ubuntu 7.04 twice and have had the same issue two times. I
installed Ubuntu along side windows xp using grub to
boot from the hd0 mbr. After the Ubuntu install the machine reboots fine.
Ubuntu loads perfectly. After several reboots it still works fine,
until I boot to windows. After booting to windows once, the machine will no
longer load grub. The computer powers up, starts the boot sequence
sees grub and then reboots.

Anyone seen this issue? I repaired the windows partition by doing a fixboot
and fixmbr. Any ideas?