Hey there! I had this same problem too! untill a while ago! It's very frustrating! I spent days on it! So, I will make your job easy by telling how to solve this. This was the way it worked for me! Here's the solution for the ones who might have this problem: This worked for me in Windows 7 Ultimate 64bit! You must have all administrator privileges!
1- Open Windows Explorer
2- Go to C:/Windows/System32/DriverStore
You will have a couple of folders and files.
You will have *.dat files and other file named: infcache.1
3- Right click every file (dont touch the folders!) and choose properties.
4- go to security tab
5- click Edit
6- choose your account and check the box: full control (see ss)
7- Click ok.
8- Repeat to every file
9- Select all the files (*.dat and infcache.1)
10- Press shift+del
11- Press OK.
12- Now, go to C:Windows/System32/Driver
13- Search for folder named usbstor.inf
14- Open it (if you have more than one, choose the most recent)
15- Copy "usbstor.inf" and "usbstor.PNF"
16- Paste those two files to C:/Windows/inf
17- Reboot your pc and voilla! :b
If Windows doesnt install them automatically go to device manager, uninstall all unknown devices and the ones with the yellow exclamation mark, then click in "check to see if there is any hardware changes" Now, Windows will install all your hardware successfully :b
Did it work?