At first i though maybe a forum issue since their have been many issues.
I tried everything you said with no problems.Its probaly your keyboard.After 5 years,yea,you got your monies worth.
When I try to scroll c/net using the keyboard keys while the windows is at the top position. The page down or end keys will not move the screen.
If I use the mouse and scroll down a number of lines and use the page down and end keys they will then move the screen.
When on the bottom of the page the home and page up keys will move the screen up.
Tried other forums (Ubuntu,Castle Cop COU) and the keyboard keys work from any position without having to use mouse scrolling.
I do not have another keyboard at the moment to try.
This is a dell by microsoft key board about 5 years old.I blew it out and turned it upside to shake out any trash. There was nothing to speak of inside.
Thanks for the help