To satisfy both you and the system

If you set your computer's screen resolution to the native resolution of the screen, and since you have the VA2226w I would bet that is 1680x1050, that would avoid the error messages.

BUT, and you have already mentioned that your eyes like whatever resolution you have now is set larger for an eyesight issue, you THEN CHANGE the DPI (the Window's screen DPI) to make things larger on the screen.

The advantage is then your screen will most likely be as clear as can be made, and everything on the screen will be large, for your eyes.

It really is the best compromise.

Now... how to change the screen's DPI depends upon your (assuming) Windows operating system.
With most Windows desktops you just right-click an open area of your desktop, and select (in WinXP) [Properties] or (in Vista) [Personalize].

In WinXP, you then select the "Settings" tab, then the [Advanced] button. There you adjust the DPI setting from the default setting of 96 DPI, to 120 DPI, or even use the Custom slider.

In Vista, you then select from the left side "Adjust font size (DPI)" and adjust the "DPI Scaling" to a larger number. The default is probably 96 DPI. Make it 120, or select the [Custom DPI] button to make it almost anything you want.