I've read through a lot of the threads here on keyboard issues. I'm wondering if anyone else has had symptoms similiar to mine: At random and variable intervals, my mapping will go screwy, the light below F10 will turn on, several keys become completely unresponsive, context sensitive menus pop open, etc. Here's the thing I haven't seen anyone else report: I can be sure one or more of those results will happen if I put pressure on or squeeze the area to the left or below the keyboard - including the black part where the media buttons are and the silver cover that is a natural palm rest. Based on that, I belive it to be hardware related. Anyone have something similar? Do you think replacing the control circuit thing as others have reported will work? Or am I looking at replacing the whole keyboard? Or something else entirely? Note that sometimes it happens even when I haven't touched or squeezed those areas, so what does that mean? Thanks!?

this usually happens if the connector(s) are lose. eiter keyboard or touchpad.
I donno how this works on toshiba laptops but you could try to remove the keyboard and re-seat the connector to the motherboard.
it is also possible that the contacts underneath the buttons are dirty. this would be a bit more work. you also need to remove the keyboard clean it up carefully. there are cleaning fluids available for notebook keyboards. I think its mostly alcohol in it because it gets dry fast. not sure but I think it was more like a spray.

bad connection somewhere. Perhaps a bad ground.