Thanks Graeme, did what you suggested - uninstalled any existing driver, deleted the related .inf files, and then when plugging in the Spyder caused a "new hardware found" box went through the hardware wizard and installed the Argyll driver from scratch. Unfortunately, having gone through copying the files etc. the driver installation reports the same failure: "Cannot install this hardware There was a problem installing this hardware Spyder3 (Argyll) An error occurred during the installation of this device The parameter is incorrect" Again a Spyder3 driver appears in the list of devices in Device Manager under "Argyll LibUSB-1.0A devices" however this time the properties dialog reports "This device is not configured correctly. (Code 1)." Try reinstalling driver and get the same result. It seems that whatever the spyd.inf file is trying to do, it is not working on my system - Win XP (but SP1 by choice, I had SP 2 kill slow another old machine to a crawl so not going there). I noticed that when the Datacolor driver was installed (and working) two files get listed under driver file details - spyder3.sys (from Datacolor) and WdfCoinstaller01001.dll. Could it be the existence of WdfCoinstaller01001.dll on my system be causing the issue? Any help appreciated. Dave > Having difficulty getting Argyll to work with my new Spyder 3 colorimeter. > The process of adding > the Argyll USB driver to the existing drivers fails. Having set the Device > Manager Hardware > Update Wizard to apply the spyd3.inf file, it seems to go so far (makes a > restore point, copies > files including the WinCoInstaller DLLs) them reports a failure: > > "Cannot install this hardware There was a problem installing this hardware > Spyder3 (Argyll) An > error occurred during the installation of this device The parameter is > incorrect" Hmm. Try uninstalling both drivers. Make sure you delete the .inf cache copies from WINDOWS/inf. > The Spyder3 driver subsequently appears in the list of devices in Device > Manager under "Argyll > LibUSB-1.0A devices" and the properties dialog reports the device is working > properly, however > it clearly isn't. The driver file details give > c:\windows\System32\drivers\Spyder3.sys version > 1.0.0.1 That's definitely wrong. > but on XP there is no UAC to mess things up. Not sure what to do next. Have > tried "jiggling", > uninstalling, reinstalling etc. but always get the same outcome. It can't possibly end up in the same state if the Spyder3 driver is removed from the system first. Graeme Gill.