Im havin windows 7 USB PRoblems can anybody help me please??

I have Windows 7 Ultimate. Since very recently an unknown device keeps popping up in the device manager every time I start Win. It's reported location is within the front USB root hub but I haven't changed there anything lately. The device status reports "Windows has stopped this device because it has reported problems (Code 43)". I can uninstall/disable it but it will get picked up again the next time I reboot. All other usb devices (mouse, keyboard, web camera, APC UPS, external drive, printer) work fine. How do I get rid of this nuisance so that it doesn't reappear?