AVR-ISP500-ISO Window 8 Setup

[Stjohn]

Hi,

I have three AVR-ISP500-ISO units, I have one unit which is working perfectly but have two units which don't work.

The strange thing is that one unit is working and two units don't work.
Ive been through disabling the Windows signature enforcement and try update the driver in Device Manager with the driver from Olimex. After I select the directory where the driver are Windows responds with no driver can be found for the device. Under device manager I see the AVR-ISP500 as an unknown device.

Ive tried this on three computers and no luck. One works but the other two don't :-(

Could anyone assist ?

Thank you