2-3 times a day my HP24f external monitor turns single color and the computer (DELL XP15) starts making a loud continuous sound and stops working. I then have to manually shut down the computer by pressing the power button. No apparent relation with software use. Sometimes it happens when I have many programs open, sometimes there is nothing at all. Sometimes early morning, sometimes end of day. It started from the first day after i bought the monitor. There is no information in Windows Event Viewer apart from "the system has reboted without cleaning shutting down first". There's nothing under "Hardware events". Solutions that did not work: 1) cleaning vents/fan, 2) updating Dell BIOS, 3) replace the cable. The monitor worked on another computer, and the computer worked on another external monitor. But this computer connected to this monitor crashes every day. I made an experiment and extended the displays across the external monitor and the computer's own monitor. After the external monitor crashed, the laptop's own monitor was still displaying, but the mouse and keyboard did not work. So it seemed the crash of the external monitor caused the laptop to freeze. The only solution for this was to force the computer to shut down. I am running out of solutions so help would be apreciated.