Drivers in desktop operating systems are not so simple as the embedded drivers, some times it take hours to solve the driver issues specially with the USB Debuggers.
Few Days back i was using arduino for low power applications, so excluded all the supporting components like programmers, UART link and used AVR ISP MkII for programming. But arduino(open source program) use libusb(opensource) where as avrstudio(copyrighted) use jungo(propietory) for usb interface. And this needs the mkII driver to be changed to libusb. mkii will be a libusb device and in device manager it will show under libusb class. Here is some supporting link
Now if i want to revert back to old driver, i tried to uninstall and delete the mkII driver(libusb), then reinstalled avrstudio again. But nothing happened. No driver found for mkII.
Now i found this blog with similar issue, they were using a debugger from freescale using jungo based usb driver changed to libusb. The part i was missing is jungo deiver install. In device manager there should be component “Jungo driver” permanently in the list whether any debugger attached to port or not. I got the location of the driver in “C:\Program Files (x86)\Atmel\AVR Tools\usb64” mine is 64 bit OS it may be usb for x86
Now another trick about how to install the driver, right click computer name in device manger then choose “add legacy hardware”. Select manually find the driver select all driver(dont srelect any specific) now choose “have a disk” . Now show the path to the folder containing windrv6.sys now it will install Jungo windriver. Now if you have avr studio installed plugin the programmer mkII, it will automatically install the mkII driver.