I found out that if one of the tabs has a PDF opened, then these keys work on none of the other pages opened.

(I had several saved tabs with sites opening everytime FF is started).

Anyone know how to correct this? Or is it a problem caused directly by Adobe?

my keyboard arrows, Home, End keys do not work...

That problem is caused by "caret cursor" and the way that Mozilla works with it. Press "F7" reply "No" to turn if off. F7 toggles the setting and you may or may not see the warning but if you do see "No" that would mean you have it on and "No" would turn it off. For a more complete resolution see

• Caret Browsing in
  http://dmcritchie.mvps.org/firefox/firefox-problems.htm#caret

See how you do with Adobe PDF files after fixing the above. You can have PDF files open by default without Firefox involved except to download them, but I expect you chose to view in your browser. You have a lot more control of reading PDF files outside of Firefox. The plug-in is what allows you to open them in a browser.

I had already tried turnung off the carot cursor and that didn't help. (And, in the warning, the "No" is always visible on my system and local.)

Right now, with it turned off, all I need to do is load a PDF in the browser and the problem is there again.

Caret browsing doesn't affect the behavior in a text input field like you experienced. An extension (theme) or plugin can cause such behavior like you found out. It may be a problem with the Adobe Reader on Windows 2000 as that is an old and no longer supported OS.

Thank you. You are right: The carot cursor doesn't have anything to do with my problem, otherwise turning it off would have solved it.

Both, not loading a PDF or deactivating the Adobe Reader plug-in solves the problem.

And, I believe you are right: The Adobe Reader version installed just isn't capatable with my system. There are no compatable versions for my system and the version of FF used.

In order that those keys work inside the PDF window/Tab, the Adobe Reader plug-in installed (9.4.0) apparently uses (at least on my W2000 system) a windows hook, (or maybe even just a simple key capture via timer), on the complete FF thread, instead of just on the PDF tab, in order to capture these keys.

When I press one of these keys in a different tab's edit box, and return to the PDF, the cursor position there changed by the exact amount of key-presses.

I have the same problem and in my case it is definitely caused by the Adobe plugin. Close the tab with the open pdf doc and the keys come back. Open the tab again and the keys have gone.