I recently worked on a Windows XP computer that came in with Webcam problems. The Logitech webcam previously worked but stopped, and all attempts to uninstall and reinstall the software was fruitless. Windows Device Manager would show the webcam with a yellow exclamation mark to indicate that it was not properly installed. The Logitech software itself would say that it could not detect a webcam attached.
However the same webcam would work properly on another Windows computer, and another new webcam would NOT work with original problematic computer, so I knew that there was nothing wrong with the webcam itself, or the third party software.
After much head scratching I finally foung the following resolution. This should apply and be helpful for problems installing all sorts of webcams, but it involves editing the registry so BE CAREFUL!
This is worth a try. Back up the registry first!
In the registry go to:
Be aware that there will probably be three or four subkeys with this name, so look for the one for Imaging Devices (you can see this for the data under the string called '(Default)'.
Now, remove any strings called UpperFilters and also remove any strings called LowerFilters.
Reboot the computer, and then try installing the drivers again. You may now find it works.