Diagnosis
This is typically a handshake issue between the monitor and your computer's graphics card, often related to the HDMI cable or the monitor trying to sync to an unstable signal.
How to Fix It
Start with the cable. If you're using the included HDMI cable, try a different, high-speed HDMI cable that you know is good. Ensure it's fully seated at both ends. Next, on the monitor, open the OSD with the joystick. Go to General > HDMI Compatibility Mode and turn it ON. This can stabilize the signal with some older or finicky graphics sources.
If That Didn't Work
The issue might be on the PC side. Update your graphics drivers. Also, in Windows, go to Power & sleep settings and make sure the display isn't set to turn off after a short time. Disable any adaptive sync settings in your graphics control panel, as this basic monitor doesn't support FreeSync or G-Sync.
Heads Up
If you're using a cheap HDMI switch, splitter, or dock, that's the most likely culprit. Try connecting the monitor directly to your computer's port to rule that out.