Accessibility Wizard

A friend is losing her sight and needs her window text
enlarged. The Accessibility Wizard provides that
capability. My friend, my wife and I are all using XP
Home on our computers. My friend and I are encountering
the same problem when trying to use the Wizard...the
choice to lower the resolution and to have the text inside
the windows enlarged, is grayed out...inaccessible. Yet
on my wife's computer, it's not. She can choose that
option...which is the option needed by our sight impaired
friend...and yet my friend and I can't choose it. Anyone
know why or what I can do to make that option available?