Most days when I turn on the computer a blue and yellow message appears on the screen informing that the resolution is not at the optimal setting and suggests a different resolution should be used. Making things more difficult is the message will not disappear. I have checked the resolution setting in Windows which is the same as the resolution suggested in the message. The computer is running Windows XP.

As you have said that the message is blue and yellow this leads me to believe that the message is being generated by your monitor rather than the computer. If this was a Windows message it would appear in a normal Windows dialog box with an OK button allowing you to close the message, whereas a blue and yellow message is generally generated by the monitor and such messages are normally quite persistent. If the resolution in Windows has been set to the optimal resolution as requested by the monitor then the other aspect which could be triggering the message is the refresh rate of the monitor. If you are using a CRT monitor (as opposed to a flat panel LCD monitor), check whether the message that is appearing mentions anything about the refresh rate. For example, if the message says something like “Optimal resolution 1024 x 768 @ 70 Hz” the 70 Hz portion of the message is the refresh rate. In this situation, you need to check the refresh rate setting for your monitor. Go to the “Start” menu > “Control Panel” and open the “Display” control panel (you may need to first open the “Appearance and Themes” category). In the Display Properties window, click the “Settings” tab and the “Advanced” button. This will show the advanced display properties, including the properties for the monitor. Click the “Monitor” tab. You should see a setting for “Screen refresh rate”. Set this to be the same value as the suggested refresh rate in the message that is appearing. Click OK and then OK again to save and close. Check whether the message disappears.

Now if the message reappears there could be something wrong with your monitor, perhaps because it is not auto-sensing the resolution correctly. You mention that this problem occurs “most” of the time when you turn on the computer, implying that it does not happen all the time. As such, the problem could be an intermittent fault with the monitor itself. A potential explanation for this could be the resolution changes which occur when you boot up the computer. You may not notice but when you start the computer, the screen resolution changes about three different times. When you initially turn on the computer the power-on self-test runs where all the hardware tests occur. When this happens the resolution on the monitor is very low (perhaps 640 x 480 or 800 x 600 at the maximum) as there are no high quality graphics or like that need to be displayed. Then, when the Windows logo splash screen appears, the resolution changes to something else. Finally as Windows loads, the resolution changes to the final resolution which you use in Windows. It is possible that the monitor picks-up on one of the lower resolutions that happens in the boot process and then doesn’t cancel the message when the resolution changes to the higher, recommended resolution. To test this theory, shutdown the computer and then turn off the monitor. Turn on the computer but do not turn on the monitor. Leave the computer for a few minutes until you are sure the computer would be booted into Windows. Then, turn on the monitor and it will detect the correct resolution and not produce any warnings. Should this work, a potential workaround to fix this problem in the future may be simply turning the monitor off and on so it clears the message and picks-up the new resolution. Unfortunately in this situation the problem seems to be related to the monitor itself so there may not be any way to permanently fix the problem, unless there is a method to disable such warnings in your monitor setup.