"Perfect with no problem" - forget about it, no one in their right mind is going to make that claim:)
We use Logic Controls PD3900U USB/OPOS displays, and I've only had one site that has had any issue. I think that one is either conflicting with the PINPad or has been subjected to some abuse by the user - they like to unplug things for some reason...
After you install the USB driver from the Logic Controls CD (NOT The logic controls OPOS Driver), you need to go into Hardware manager and look under "Ports" to see what COM Port was assigned to the pole display. It's usually COM3, but I've seen it go up as high as COM5 - you always need to look and see what was assigned...
Set the pole display up in the MS OPOS configuration and test it.
Does your display work sometimes? Like can you do a CheckHealth? Does it display the Welcome message when you open POS? Is this error only occuring at certain points, or is the device just always blank?