The problem seems to be that windows either does not load a driver or tries to load the wrong driver, In the research I have done Microsoft seems to lay the blame rightly or wrongly on the drive manufacturers and suggests that the drivers for the devices should come from them. We both know that the drivers are included in Windows but the problem is how to make Windows load the right driver for the right device. Up until now the tutorial I posted has had a fairly high success rate in solving this problem but I am unsure what to do with the unsolved cases.
At the moment the only help I can give is the tutorial, that should, by the way be carried out on each affected PC ( I forgot to mention this before) and from my own experience I suggest one device per USB port as only one driver will be installed for each port avoiding Windows trying to load the wrong driver. Or even buying all devices from the same manufacturer.
I am at a loss as to what else we can try but I will continue looking for an answer and will let you know if and when I find one.
One last thing, do you use a USB hub? if yes is it powered? I cant verify this but I have read about similar problems where USB hubs that do not have a power supply are being used.