Unable to boot with Ubuntu and Windows 7 - grub bootloader getting removed
I have recently purchased a new laptop, which came with Windows 7 pre-installed. I immediately installed Ubuntu alongside it with a dual boot.
At first it worked fine, but when I restarted after the first time I used Windows, I ended up with an 'Operating system not found' error. I was able to reinstall the Grub bootloader using an Ubuntu Live CD, which appeared to fix the problem, but the next time I loaded Windows 7 and rebooted, the problem reappeared.
I think the problem is that Windows 7, for whatever reason, is somehow removing or disabling Grub. I have searched elsewhere but have not been able to find a permanent solution. Any ideas?