I had a similar problem installing a bluetooth usb dongle. Every time I tried to (re)install the driver, Windows tells me: The driver installation file for this device is missing a necessary entry. This may be because the INF was written for Windows 95 or later. Contact your hardware vendor. - I tried to uninstall unnecessary (hidden) drivers having the devmgr_show_nonpresent_devices set. - I tried to run SFC /Scannow in order to verify that all protected Windows files are intact. - I tried to uninstall all USB Root Hub drivers. All without success, finally I just started reading the driver's INF file and noticed this section: [BCBTUsbDriverInstallXP.NT] Include=Bth.inf Needs=BthUsb.NT So I went to see if \Windows\inf\Bth.inf existed... It didn't! It was renamed to Bth.inf.0001. I think some uninstaller (WIDCOMM?) may have done that, anyway, renaming the following files back solved my problem: - Bth.inf.0001 --> Bth.inf - Bth.pnf.0001 --> Bth.pnf Thanks Mordac85 for suggesting to search the INF file for clues to the nature of the problem!