SilkTest Classic: Why does Sys_FileOpen() command fail when executed on Windows 8.1?
The reason why this error is thrown on Windows 8.1 when the same command may work on other operating systems is because the specified directory is protected by 'User Account Control' on Windows 8.
The solution is either to disable UAC or choose a file location that is not protected by it.
Note that on Windows 8 and 8.1 UAC cannot be completely disabled through the Control Panel. If you choose to do this you will need to navigate to the following Registry key:
Key Name: EnableLUA
Reboot the machine to apply the Registry changes.