A couple of other things to try:
1. Confirm that you have selected Front Port on your scanner and set that to 4800. That's done in the settings menu, set serial port. (I found that the hard way - I was using rear port for GPS purposes on my 996s, a similar scanner, and forgot to change the port for programming purposes).
Some times a slower speed works better. If 4800 works, then try higher speeds on the scanner settings.
2. Power down your computer and re-start. Sometimes, particularly when installing/uninstalling/installing drivers, a comport gets confused. The original driver may be "on the mind" of the comport. A power-down/power-up cycle can clear that fog.
If these don't work, and others may post some additional suggestions, then cable replacement may be the next step.
I don't think it is the chipset issue as the HXD is only needed for Windows 8. At any rate I'm sure the HXD is "backwards compatible" and will work with Win 7.
It is possible the cable may be defective, such as a broken wire or bad connector where it mates to the front port of the scanner. I suspect the USB end is working as when you checked the chipset version you received an appropriate response.