After installing Ubuntu 11.10, it boots perfectly. But when I select Windows 7 from the GRUB menu, it restarts after showing the boot logo. I tried to repair the boot loader but the process failed. Then I decide to repair with system recovery disc. There I realize the system is unable to find any existing system. Then I boot into ubuntu and here I can see all the existing drive (with all content). All drives are still NTFS file system (I have 4 drive: 3 are NTFS another 1 is ext4). Tried to repair with gparted partition tool, but came with no luck. Also tried to reinstall windows but installer don't show any available drive. What to do? (something to do with Ubuntu?)