Im thinking that this is a driver issue because clearly the port and software was working with the Rev C device, but not Rev A. Check out this link on the P&E Microcomputer Systems site
here. I'm thinking that you have a USB 2.0 driver, which hasn't got a clue about a USB 1.1 device. I'd go their downloads page
here and download their hardware interface drivers. Then do an install and see if that provides the proper driver for your Multilink Rev A.