I seem to be having the same problem. I have both Digisparks and Pro's, and neither work correctly. Running the driver installation shows an error installing "Digistump LLC (usbser) Ports (08/16/2014 1.1.0.0)" but it does install "Digistump LLC (digistump.com) (usbser) Ports (09/02/2014 5.1.2600.1)".
When I plug in either a Digispark or a Digispark Pro, in Windows Device Manager, it says:
The drivers for this device are not installed. (Code 28)
A service installation section in this INF is invalid.
To find a driver for this device, click Update Driver.
I even tried "Update Driver" and tried to point it to the exact driver to load, with no success. I'm running Windows 8.1 x64 Pro, and this computer has never had any Arduino software loaded.