Thank you Gav. I have an enhanced USB controller and it is working correctly it reports. I checked the BIOS and USB2 ports are enabled.
Not being an expert I am loathe to flash the BIOS. It is rather like altering the REGISTRY which I do reluctantly, but It is backed up. If I mess up the BIOS I am not sure how to recover.
Most of my USB appliances are recognised and working happily. Since I only have trouble with two memory drives which are not recognised on this machine I am inclined to leave well alone!!