Problem has now been solved
Once more I have been given a weird problem. This time it is with Firefox only. And even more weird: it is no matter what Firefox version I am using; 3, 4, or 5, Safe Mode/All AddOns Disabled, or not!
The navigation hotkeys have gone missing from my keyboard when I use Firefox. PgUp/PgDn and Arrow up/down/right/left are all out of order; they do nothing, no "fast scrolling" (or what you call it). But it is only when dealing with Firefox; with every other program and in every other situation the keyboard is working normal as it is supposed to.
It has taken me some days to test all combinations I could think of, (including removal of the latest new programs and updates), except for the total
removal of Firefox, and I still don't have any idea what have gone wrong. Can "you" think of a reason and/or a solution, please?