I had my little netbook on battery, and while it was running fine, I then plugged in the power adapter, (while on).
Suddenly the pointer froze, touchpad does not work.
Rebooting did not help.
The keyboard seems fine, but I can not point and click on anything.
What could be wrong ... ?
OOPS ! Nevermind.
I messed with the function keys.
I am guessing that I switched it over to an 'external mouse' ... ?
Anyway, it works again !