What downgrade are you talking about xRayeR? NUSB uses Win ME USBSTOR.SYS (v. 4.90.3000.1) since NUSB 3.1 and up to 3.3, so there's no downgrade in it (read again the 1st post in this thread). Check for yourself, here are direct download links to two bona fide sources for it: NUSB3.3 (at MDGx) and NUSB3.3 (at technical-assistance.co.uk). What version of USBSTOR.SYS were you using that suddenly stopped working? If you mean USBSTOR.SYS (v. 5.0.2195.6655) from NUSB 3.0, it also needs WDMSTUB.SYS, also from NUSB 3.0 to work. To install it, you might just drop WDMSTUB.SYS from NUSB 3.0 in your %windir%\Sytem32\Drivers directory and edit the line in USBSTOR.INF that reads:HKR,,NTMPDriver,,USBSTOR.SYS to read, instead: HKR,,NTMPDriver,,"WDMSTUB.SYS,USBSTOR.SYS" and redetect all USB devices. You can get NUSB 3.0 (here). Observe that all the links in this post are for English versions of NUSB, but WDMSTUB.SYS is language neutral. Please, in uninstall file _nusb.inf (3.0): ;wdmstub ;HKLM,System\CurrentControlSet\Services\Class\System\0000,NTMPDriver,,"update.sys,wdmstub.sys" Why REM (? It's OK?