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 Store/File Repository/
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