Does pressing the space bar again toggle back to the original resolution? If so, that might be a change from the screens native resolution to an external resolution such as might be sent to another type of monitor or LCD projector. Your 3 year old might have created a custom "hot key" other than whatever Toshiba might normally use. It's probably possible to disable custom hot keys by finding the right service or entry under msconfig to shut it off. I can't tell you what it's name would be but should be somewhere in the Toshiba help sections.
I have a 2+ year old Toshiba Satellite Laptop running XP Home Edition. My 3-year-old pushed random keys on it over the weekend, and now my space bar doesn't work. When I hit the spacebar, it now changes the screen resolution instead of making a space. This happens no matter where I'm at (desktop, any application, etc.).
Has anyone seen this?