A4 tech web camera  

1. Check your memory and videocard. Maybe you don't have enough memory or you have low graphics settings to properly render video on your screen.

2. Check your usb connection, maybe it's loose that's why data transfer is intermittent.

3. Try re-installing your webcam's drivers. Or look for new versions of the driver.

4. Try installing the webcam on another PC. If it works perfectly fine in another PC, the problem's your PC, not the cam. If the problem appears on another PC, it's probably time to buy a new webcam.