normally, this is related to power on detect signal feedback, either because loose connection of mechanical contacts corrosion or failure, please include brand and other technical information to help you further with your issue
It would be usefull to know which camera. Are you working under a service contract? If so, it is best to ask an engineer to have a look. You can start by checking the temperature of your camera to see if it is properly cooled and see if your power supply is connected thightly. If these are the case you could try restarting the software, or if this does not work the entire microscope and camera computers (Be aware, there is a specific procedure and order to this). Good luck.