I recently upgraded from 13.10 to 14.04 and now I have to unplug the keyboard and mouse and plug them in after the system is booted. I have a Razer Black Widow keyboard and a Corsair mouse. My system is a dual boot Ubuntu/Windows 7 - i7-4770 in a Dell XPS8700 I have no problem with Windows and the USB problem(I assume it's a USB problem) only started after this upgrade. I'm not very familiar with Linux software repairs although I've used Ubuntu for years. I'd like to continue to use it without wearing out my USB ports
I was having the same problem with my XPS8700 in a dual boot with Windows 8.1. What fixed it so far was disabling acpi when booting Ubuntu.
It worked for me, hope it helps!!!
Here is my answer long and short, Long first, Look in the box your PC came in for your USB and motherboard drivers, they help. In specific the USB drivers for the ports that are on your specific motherboard.
A trick I learned just to get Windows going, when it freezes at the log in screen: plug a USB mouse in the USB 3.0 port, leave it in while you push the kill button, unplug it after computer shuts down and reboot. Hard to believe but that will get it going one time.
Think, if you do not have a GPS, or special device that requires Windows.
Install Ubuntu on the disk, let it kill Windows and you will have a trouble-free computer. Ubuntu has better office, video, and things you pay for in Windows. I use only Ubuntu in my work computers, I can't afford the problems with Windows.