First I would suggest that you install the latest drivers for the built in webcam by visiting the laptop manufacturers website and locate the latest drivers for the webcam install it and restart the computer check if it works.
If the above step does not fix the issue would suggest that you repair the camera assistant software from the control panel.
Click on Camera Assistant in Control Panel/Programs/Uninstall a Program. Click on Camera Assistant Software. Then choose Repair.
If the above steps does not fix the issue would suggest that you contact the laptop manufacturer for more information.