Interesting problem; I rebooted my computer last night to be greeted with the ol’ INSERT BOOT DISK AND PRESS ANY KEY message on my computer that has Linux and Windows in a dual-boot. I’m not 100% certain how to reinstall Grub without reinstalling Linux, but I was able to do a fixmbr/fixboot from the Windows recovery console and get back into Windows. Does anyone know if it is possible/how to reinstall grub so I can get back into my Linux partition without reformatting?

Alright, maybe this’ll sound needlessly complicated but I’ll try to explain.

1- Get an ubuntu liveCD if you don’t have one already.
2- When you get in a gui, open a terminal and make a dir, name it wheatever you can.
3- Mount your linux partition on it
4- Type “chroot /dirwhereyourlinuxpartitionishere”. That’ll make said dir /, effectively getting you into your old ubuntu system
5- From there, just sudo apt-get grub or do whatever else you’d do normally. Maybe check grub’s config file or run debian’s automagical updater (was it grub-update? I haven’t used it in a while)

That acutally reminds me of how I deleted pam-login once… (don’t ask how or why, gentoo users are weird >_>) and had to use a similar method to be able to log into my system again.