According to the manual, you can scroll through the inventory one "page" at a time using the page up and page down keys. This does NOT work for me. Does it work for anyone?

They sure do for me, just like Home and End.

Hmm, I figured it out. Numlock has to be off BEFORE launching the game. Though why Numlock would affect the PageUp/PageDown which are NOT on the keypad is beyond me.....

That's strange indeed. I don't have to turn it off.

Hitting pause/break in-game seems to toggle the functions of pgdwn/up, if not other keys as well. I didn't test it much, but it closed my inventory screen instead of scrolling. Hitting pause/break again changed it back to working fine, of course.