Maybe it was one of the settings on the monitor itself (CRT rotating button, TFT options menu).
Driver settings, or maybe even obscure windows settings (when i try ctrl + alt + drectional, nothing happens..)
check those, you can always try to connect the monitor to another computer (if it still occurs, it's a hardware setting, otherwise it's a software setting).
Maybe if you can give us some more detail (graphics card, monitor details) we could help you google (or someone has the same, and could test it) a fix.
I like the kid though, reminds me of myself at that age (ok, I mashed my dad's commodore :P not his PC... big difference), hahahaa.
good luck, let us know.
regards,
PS: if people wanna argue about how they hate kids or not, please make a new topic :P