* Power off the PC
* Power off the monitor
* Disconnect the power cord from the monitor
* Disconnect all monitor cords from the PC (USB, DVI, VGA, DisplayPort, HDMI, etc.)
* While disconnected, press and hold the monitor power button down for 5 seconds
* Reconnect the DVI cord to the monitor and to the PC video card
* Reconnect the power cord to the monitor
* Power on the monitor if it does not power on by itself
* Power on the PC
* Press the monitor Input Source Select button and choose DVI

Does the OSD still appear at random?

Check your private message.

Thanks for your help.

The problem is the light of electric light.

Now it works perfect. Thanks

Is that a standard desk lamp? What model? How close is it to the monitor?

A normal desk lamp it close the monitor about 20cm. 

When I remove the desk lamp the monitor works good.