I did download the driver from https://www.olimex.com/Products/AVR/Programmers/AVR-ISP500-ISO/ (https://www.olimex.com/Products/AVR/Programmers/AVR-ISP500-ISO/),
unpacked it to C:/temp and tried to use Windows Device manager to install it .
It finally fails with stating that it found a driver for the device but can not install it
because a hash value for a file in the catalog file is missing.
Any ideas how to fix that problem ?
Did you temporarily disable the automatic driver signature enforcement before trying to install the driver?
What Windows are you using?