Most likely cause is that you suffered about a 2 second power outage or brownout. If there is a power outage of only a few seconds often the camera will go black. As far as I know there is nothing you can do remotely to fix it. I've tried resetting it via telnet, upgrading the firmware, changing all the CCD and video settings, without result. The only way I know to fix it is to physically unplug the camera for about 15 minutes. After that it works again. I was coming here specifically looking for a fix for this problem, as it just happened to one of mine that's about a thousand miles away. On one of the other's I've resorted to hooking it up to both a UPS to prevent these short term outages or brownouts and an internet enabled power strip so that I can remotely shut off the power if it still happens. It's a real pain in the butt, and it should have been fixed, but I guess these are EOL now so no more fixes. My hunch is that the problem is in the CCD circuit, which is why only a full power down will clear it.