I have a lenovo g580 with windows 8 installed along with Ubuntu 13.04. I was using dual boot without any problems for one year. About a week ago my ubuntu stopped booting and instead i get booted to grub rescue.
My Ubuntu 10.10 system suddenly froze/crashed for no reason and I had to hard reboot my computer. Surprisingly it doesn't load anymore and stay stuck on a grub rescue prompt after an "unknown filesystem" message.