If it's not even getting to loading the system (the errors appear after GRUB), you may want to try reinstalling GRUB using the Super GRUB Disk. It's possible the UUID on the drive changed when you modified it with the install, so GRUB may be looking in the wrong place for the drive.
http://www.supergrubdisk.org/
It's a nice little disc to have, it can be a little strange, but I think you can muddle your way through it and try a few different options. The best option would be to just reinstall GRUB with it for the dual boot system and have it autodetect the installs.