Help! Page Up/Down Buttons Malfunctioning

[EightZeroZeroDelta]

Hello all,

I have downloaded the new Firefox 4 and since my Page Up and Down keys do not work. Occasionally they will both function properly, but randomly the Page Up will act as the Back button (just like the Backspace key) and Page Down will go forward one page. After searching, I found that turning off Caret Browsing by pressing F7 is supposed to help. I also saw that going through the Options tab and turning off 'Always Use the Cursor...' option should fix it. No such luck for me.

Again, this malfunction occurs randomly and for long periods at a time. Rarely do the Page Up/Down buttons work as they should.

Thank you so much in advance!