That is an odd problem. I'm sure your son is long since home and back to school again, but what did you do to change the default browser in the first place? Did he know how to successfully restart the computer and change the browser himself?

The typical approach is to go to the Start button (bottom left corner) and open up the default program setting screen from that first box that pops up or from within control panel. And on the program you have installed click on it and tell it it may be the default browser. You can also set the browser as default from within the browser itself.

SRS