|I don't recall ever running into an issue where the screen didn't reach the edges. |
If it uses a separate monitor there might be some settings (buttons) on the front that got altered.
I never used any zooms on mine, but simply set it to the native resolution for the screen, or lower if I found everything looking too small.
Hard to know what got pressed but most Display settings are accessed by right clicking the desktop and going to Properties - hard to imagine baby managing that one but you never know. I might fire up my old W98 later and remind myself about the settings details.
Always pop back and let us know the outcome - thanks