GRUB2 error: unknown filesystem from reinstall

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http://askubuntu.com – (Sorry if some of this info is irrelevant, not sure if how much of this will matter or not) So I was reinstalling Ubuntu 12.10 with the same USB I had used to install it the first time (dual boot with win7). I initially had a grub error booting into windows (but not ubuntu), but I could still boot into windows by switching to the windows bootloader in the BIOS. So I ran boot repair in ubuntu and everything was fine. However there were some sound issues, I tinkered with alsa and ended up breaking it more, so I decided to reinstall. When I booted from the USB, I got the option to remove the exi (HowTos)