Brand New My Book Essential WDBACW0030HBK-01 doesnt show up in my computer

Just a further update: I plugged a 2TB WD My Book Essntial into this PC and it works perfectly! That proves no USB issue, no driver issue as all is well. As soon as you plug 3TB drive in, it isn’t seen. Device manager shows it just as “disk drive” and with “no driver installed” On a separate PC with the exact same spec and build of windows xp it works perfectly within seconds. Just dont get what is clashing with it on our other machine. Have even tried loading within windows safe mode and also with everything restricted right down in msconfig. Still no joy! Any ideas anyone on how to perform some basic troubleshooting??