Eric the Red

Good call Andavari, Windows versions affected are ... 2K(all versions), XP(all versions), 2003(all versions), Vista(all versions), 7(all versions) i.e. not related to Windows version, only related to drivers that use the WDF co-installer (WdfCoInstaller01009.dll). Possibly/probably applies to other versions of WDF co-installer but I can't test. Eric

All, Due to the wonders of the way that Windows Drivers (written with the Kernel Mode Driver Framework, KMDF) are installed, if you let CCleaner delete this key then you will no longer be able to install *ANY* devices (or run updates for any devices) that have been written using KMDF. You cannot correct this error by trying to install/reinstall a device because it won't work (however, if you have another PC with the relevant entry, you can regedit export the key and then regedit import). You do not need to keep the directory containing the uninstaller, but you do need to keep the registry entries. Problem: Uninstaller Reference Issue Data: "C:\WINDOWS\$NtUninstallWdf01009$\spuninst\spuninst.exe" Registry Key: HKLM\Software\Microsoft\Windows\CurrentVersion\Uninstall\Wdf01009 Can I suggest that Piriform add this to a 'do not delete' list. Eric