Windows Server 2008 R2: NTLDR is missing

Just use the search engine of your trust and let it search for "Windows Server 2008 NTLDR is missing" and you will find many occurences of this problem. It happens every time I do Windows Update or if I connect my other hard disk and try to boot Windows Server 2008 by GRUB (which normally is possible easily). Then I have to search for my Windows Server 2008 DVD - yes, Microsoft still uses technology from the 1990s to distribute their OS, while booting Ubuntu means just entering 4 lines in my grub.cfg and it boots off the desired ISO file from my (much faster) hard disk - and boot it while having my second hard disk disconnected, doing some quirky repair, rebooting and boot again from DVD, repairing again, and rebooting and hoping. Hm, is that the way I expect my computer to work? No. So, I won't install Windows any more on real hardware, I only will install it inside virtual PCs where it is "alone" and can't do anything bad (although I still like Windows Server 2008 R2, it's basically a great product, just the boot loader sucks).