Problems with Page Up, Page Down, Home, and End Keys
 

I'm using Mozilla 1.6 on Windows 98SE.

I view news groups using Google Groups. After a short while, when
viewing a thread the Page Up, Page Down, Home, and End keys stop
working. The scroll wheel on my mouse will allow me to scroll, but
not the above mentioned keys. If I highlight some words and select
Edit, the Copy feature is not selectable.

If I close Mozilla and reopen it, the above mentioned keys will
function, at least for a short while.

No changes in software on my machine lately,

Any ideas what might be causing these problems and how to fix them
without having to close Mozilla?

Thanks for any help.