run regedt32 as Administrator
in the registry editor find HKEY_LOCAL_MACHINE\system\ControlSet001\services\usbstor
expand (double click) the Start key
change the hex value from 4 to 3. There should be no need to close the editor.
Do the install.
change the hex value back to 4(or leave it at 3 to make this permanent).
close the registry editor.
Locate the files usbstor.inf and usbstor.PNF
Ensure that both of these files security properties have administrators with full control