A green screen is usually due to lack of power to camera.
Try removing any other USB devices plugged into computer.
All USB ports on a system share an alotted power "pool."
Try an alternate USB port on computer, preferably on back.
Ports on monitors, keyboards, front of computer, etc are often underpowered.
Try installing a powered USB 2.0 hub (connected to a USB 2.0 port).
This provides standalone power to device, not sharing resources with other devices.
Not all powered hubs are created equal. Digital Doc powered hubs have been tested for use with our cameras.
We have had outstanding results using powered hubs manufactured by Cables-To-Go as well as Belkin.
We have encoutered multiple reliabilty issues utilizing hubs manufactured by D-Link and Gigaware (RadioShack).
Some software will display a black, blue, or green screen if video capture card is installed.
Device needs to be removed through device manager, then physically removed from system.
Alternatively, device can be disabled through device manager and physically remain in system.