Steps to solve issues with screen resolution when the monitor sleeps.
When the monitor is turned off (e.g.: after 10 minutes by Power Setting when it goes to sleep) a "USB/Device change sound" is heard. This goes back and forth (pairs of sounds 3 seconds apart - "plugged"/"unplugged") every ~20-40 or so seconds.
After the "unplugged" sound, when the monitor wakes up (e.g.: by moving the mouse), the screen resolution is changed and incorrect with black bars at top/bottom of the screen, illegible font, etc.
Follow these steps to rule out hardware issues:
- Check the cable connection of the monitor and the one connected to the system to ensure proper connection.
- Test a different video cable.
- If the monitor has a built-in USB HUB with USB devices connected to it, disconnect the USB devices and test the behavior.
- Test the monitor with another computer.
- Use another monitor that is known to be working to exclude monitor issue.