Dual Boot - Keyboard and Mouse NOT Working after switching OS

My operating systems are:
Windows 7 Ultimate 64-bit (Default OS)
Windows 8.1 Pro 64-bit

Motherboard:
ASUS MAXIMUS VII HERO Intel Z97

Problem:
Mouse and keyboard stop working at the logon screen (usually even sooner at Starting Windows loading screen) when switching from Windows 8 to Windows 7. But when you switch from Windows 7 to Windows 8, they still work but not vice versa. They don't work at the Windows 7 installation menu either when booting from Windows DVD.

I have tried:

• Unplug mouse and keybaord. Nothing.
• Plug-in another keyboard. Still nothing. It' s like they are being turned off immediately I plug them in.

Known temporary fixes:
1. Turn of PC and disconnect the power cable. Put the cable back in and start the PC. Mouse and keyboard are now work again. If you switch OS again you have to repeat these steps.
2. Go to the BIOS settings and change default settings related to USBs. Like USB Support to "Full Initialization" (default: Partial Initialization). Save changes and restart PC and they should work again.

Question:
How can I fix it so that mouse and keyboard always work when booting to a different OS?

Thank you very much for the resolution on this. As I was also running in to the same issue when multi-booting from Windows 10 default, I was rather puzzled since the multi-boot was working. USB drivers were not loading.

I set Intel xHCI Mode to "Auto" and it is working fine now.

Heh, even Microsoft had no clue.

Thanks again! Very happy now with my dual-boot between Windows 10 and Windows 7.