Win.ME Background not full size…

A friend of mine has a computer running Windows ME. During the boot-up process all is fine until the Desktop appears, it stretches accros the screen aproximatly 7/8 of-the-way accross and will not go further. Could this be adjusted throught the Control Panel [Display] or would you say its part of the adjustments of the monitor itself?

By-the-way, if it makes a difference, it’s a Compaq.