Hi Roger-
The problem you are describing sounds very much like a power issue on that line. Is that a long cable run?
If it is longer than 180 feet, you might be experiencing voltage drop on that line. This is magnified at night when the IR LEDs come on. (Voltage drop increases as the load increases)
Have you tried swapping a known good camera to that cable? That is the best way to troubleshoot the cable and power. Sounds like you have isolated the issue to that particular cable/camera - now the last step is to determine if it's the cable or the camera. Swapping it with a known good camera is the best way to sort that out. That will also show if that camera is good on a different line. That would be my first suggestion to troubleshoot it.