Thanks for your link, Gregory. Turns out I didn't give enough information in my original post - and after thinking of the right terms, a Google search found the problem. I was affected by bug 477104, fix and cause here: https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/477104 in case it will help someone. I was running Ubuntu Netbook Remix 9.10 via Wubi (critical missing info in my original email). Wubi + kernel update = broken grub2 & left at bootloader. In the future, I'll need to follow any major updates by running sudo update-grub2. If this happens to anyone else, I fixed it by running:
set root=(hd0,1) loopback loop0 /ubuntu/disks/root.disk set root=(loop0) linux /boot/vmlinuz-2.6.31-17-generic root=/dev/sda1 loop=/ubuntu/disks/root.disk ro initrd /boot/initrd.img-2.6.31-17-generic boot
Once Ubuntu booted successfully, I had to run sudo update-grub2 to prevent the issue from recurring at next boot. Obviously, the versioning will vary; I also had to rollback to the previous version of vmlinuz and initrd. I've seen comments that the first 2 lines aren't necessary, but I needed them on my system. Hope this helps someone out in the future! Cheers, - Eric