Simple solution ....... at least it worked flawlessly for me.
It seems that I spent more than a couple of days trying to resolve this one, including updating "repairing" WindowsXP and a long phone call to Logitech Tech support, all to no avail.
The simple solution is to uninstall any and all previously installed Logitech drivers (even going into your registry and deleting all relating registry entries pertaining to your Logitech Webcam. Then with your Webcam plugged into your USB port as an unrecognized USB device, do a Windows update. Viola, your problem should be solved.
My was with the installation of driver v11.80.1048.0 for my Logitech WebCam Communicate STX.
I'm now clean of any extraneous Webcam software, and my Webcam works "flawlessly".
My advice is to stick with WindowsXP drivers, and not anything that would be downloaded separately.
cheers,