Your camera may not be getting enough power. Make sure you're using the original power cable that came with the camera. If your camera is part of an outdoor Low-volt setup and powered by a Low-volt power supply unit, ensure that the PSU isn't overloaded: for example, a 40 W PSU can only power up to 40 W of devices. Add the wattage of your outdoor lights, and then add 10–15 W for the camera.