A lot more information is needed. What server, PC NA or PC EU. What are you doing and what is happening around you at the time is helpful. Have you had the same issue occur with all addons turned off?
I would suggest adding that information here, but also create a ticket on the situation with that information.
BTW, restart PC before any of this. If the issue is with your equipment it is not likely the monitor, but a device on the PC. Restarting the PC is the first step in tech support.