A 20mm black vertical strip runs down the right-hand side of my monitor. When I move the mouse to either side of the screen, the display ’scrolls’ horizontally, allowing the previously hidden portion of the screen to be displayed. However, if the black strip was not present this scroll would not be necessary! The problem briefly corrected itself, but the display was blurred. How can I fix this problem for good? The computer is running Windows XP.

This problem can arise if the display resolution is incorrect, the incorrect monitor drivers have been installed, or the incorrect video drivers are installed. First, check the resolution of the screen. Go to the ‘Start’ menu > ‘Control Panel’ and open the ‘Display’ control panel (you may need to first click the ‘Appearance and Themes category’). In the window that appears, click the ‘Settings’ tab. Check the ‘Screen Resolution’ and try changing this setting, then click ‘Apply’ to see whether any other resolutions display without the black bar. Be aware, some of the higher resolutions may be out of the range which your monitor can display. If your monitor goes black and doesn’t display anything, don’t do anything and Windows should automatically abort the change in 15 seconds, returning you to the previous resolution.

Should changing the resolution not resolve the problem, the drivers for your monitor could be incorrect. Check which monitor drivers are currently installed by clicking the ‘Advanced’ button (on the ‘Settings’ tab in the Display control panel). In the next window, click the ‘Monitor’ tab. Under ‘Monitor type’ the type of monitor attached to your computer should be displayed. If this displays the correct name of the monitor, or displays ‘Plug and Play Monitor’, that should be fine. However, should the monitor be the incorrect type you should install either the correct driver, or the generic Plug and Play Monitor driver. To do this, click the ‘Properties’ button under the monitor name. In the window that appears, click the ‘Driver’ tab and the ‘Update Driver’ button. Follow the prompts to update the driver.

Finally, it is also possible your video drivers need to be updated. You should try visiting the website for the manufacturer of your video card to check whether any updated drivers are available. If so, download and install the drivers. This is usually a relatively easy process, as the drivers usually include an automated installation program.