There is a vicious bug in Windows 7 I have discovered the hard way.
If you have a disk in the old MBR format (UEFI prefers GPT) containing an extended partition with logical partitions, Windows 7 will crash on boot while booting in the UEFI mode. It does not matter that the disk may not be even accessed, just being connected will cause the crash.
I had to move all my data to a backup disk, change the empty disks to GPT, and move the data back to make it work. Microsoft offers a solution, but it comes as a patch to the installation CD - basically, you have to make and burn your own patched ISO.
In general, UEFI is not a good technology. The main drive behind it is the attempt to lock your computer, because uefi supports booting to so called "trusted" platforms only - basically, it containts a set of public keys (provided by the manufacturer), and will boot only to an OS that was signed by one of those keys when "Secure Boot" is enabled. The original specification stated that there must be an off switch for Secure Boot on desktops, but that it must ALWAYS be ON on mobile platforms, so that the manufacturers could dictate what OS is eligible and what is not.
It's basically another creepy-crawly move to snatch away another of your remaining rights - the right to boot whatever you want on a hardware device you have purchased.