If your monitor (especially the tube) for many years may have failed any of its parts. Any changes in settings that will not fix it. If the monitor is not over the warranty, give it to a service center. A better - think about purchasing a new device.In that case, if you are worried about the flickering on the monitor, change the refresh rate of the screen. By default, the screen is updated once per minute. For some monitors this is not enough. Call feature Screen." To do this, click the right mouse button at any free part of the "Desktop" and select menu item "Properties". This will open a new dialog box.This window can be opened in another way. Using the start menu, open "control Panel". In the category "appearance and themes, select any of the jobs or click the Screen with the left mouse button. In the opened window, go to the Settings tab and click Advanced. In the Properties window Module, connect the monitor and the [name of your graphics card] open the" Monitor "tab and set the marker in the field "to Hide modes which the monitor cannot use". In the group Settings of the monitor, select the desired refresh rate by selecting a value from the drop-down list. The higher the frequency, the less flicker a monitor. Click on the "Apply" button, confirm your changes and close the window. Cause unstable operation of the monitor may be problems with the video card or the wrong choice of driver. Install the driver to the monitor with the installation disc, which is included in the delivery kit of the monitor. If the disk has been lost and you are going to download the driver from Internet, please check the model of your monitor and install software only from official website manufacturer.Sometimes display issues can be caused by other equipment located in the vicinity of the monitor. In this case, make sure that devices emitting microwaves were away from your monitor.