I've never messed up my grub, so I'm not sure if you're having an installation error, but it would probably be easier to use the live cd to edit /boot/grub/grub.conf (it can be located in other places but that's probably the most common). If your distro is good, it will contain pretty straightforward comments in the file to explain whats happening.
You should also check your /etc/fstab entries to make sure you're not referencing the non-existent windows partition.
