There should be two drivers under Jungo section in Device Manager:
1) A tool specific driver (AVRISP MKII in your case, or it could be AVR Dragon or other tool) that is installed when you plug in the tool
2) WINDRIVER that is installed by AVRStudio.
Your problem is usually caused by not selecting install Jungo drivers during AVRStudio installation, so you need to uninstall and re-install AVRStudio, making sure you select Jungo drivers. This should work with all versions of AVRStudio.
There is a shortcut if you don’t want to have to re-install AVRStudio 6 which takes ages.
1) Run cmd.exe as administrator
2) Change directory to C:\Program Files\Atmel\AVR Jungo USB folder (maybe Program Files (x86) on some PCs)
3) Select either usb32 or usb64 folder
4) Execute this command