Was that last video of the first computer?
It may just be an issue of a poor USB subsystem. I know that you're limited on ports on a laptop, but as Ron stated, be sure it's not plugged in to a 3.0 port (they have a blue tab inside instead of white). In your 'C:\Program Files (x86)\ShopBot\Diagnostics' folder, there should be a file called 'USBVIEW.EXE'. Run that to see what kind of controller the shopbot is on , enhanced or standard (this is easier than device manager to view). If at all possible, you should try to have the spindle control and the control box on separate controllers. You can swap them around and hit file/refresh in USB View to see were they have moved to. If not sure which one is which, unplug the spindle control and leave it out while checking the control box.
That Packet_ET is good on the test laptop.
I've never been a big fan of laptops for running these, but understand the appeal. Make sure that all power saving features are turned off and if possible, you may be able to turn off processor throttling in the BIOS.
For a test of the settings from one computer to the other, you could save the settings on the one that works and load them on the other. 'US' on one and then 'UR' on the other.