25 hours ago
I attempted to install Ubuntu 13.04 with Windows 7 64 bit on an HP DV7t-7000 notebook. The Ubuntu installer was unable to identify the existing Windows installation. I have two hard drives installed and I think it did not even see the first one possibly because it is GUID and the notebook is using UEFI.
22 hours ago
I had similar issue which I fixed with boot-repiar:
sudo add-apt-repository ppa:yannubuntu/boot-repair
sudo apt-get update
sudo apt-get install boot-repair
I have Ubuntu Raring + Windows8 both working fine.