Down Arrow not Functioning Properly

Question

The down arrow key is not doing what it is supposed to do. When pressed, nothing happens. For example, in Firefox it doesn't scroll down. In Word, it doesn't scroll down. In games, it doesn't control anything, and isn't recognized when pressed or rebound.
HOWEVER, the button clearly still functions. It still does other things. For example, in Firefox, when command+downArrow is pressed, it scrolls to the bottom of the page.
The problem also occurs when using just the laptop with no external hardware connected, when using an Apple blue tooth wireless keyboard, and when using a wireless usb Logitech keyboard. Both these external keyboards function perfectly in every other way.
This problem seemed to arise after I first plugged in my wireless Logitech keyboard (that is not OS X compatible on the box, as far as I know). When performing the keyboard set up, I could not complete the "keyboard type detection test" (because my shift control and alt keys were not side by side) so instead I chose the "standard us keyboard" option.
So why has my down arrow become unmapped has a "move thing down" button? And how can I fix it.
Thanks
PS: Completely unrelated (I assume), but I recently had the logic board on the MBP replaced, after a fatal crash during World of Warcraft play that rendered the computer unusable. When the power button was pressed, it beeped SOS on a black screen. Lots of troubles here, I am not too impressed.
Message was edited by: Foliot

Answer 1

You can't brick your MBP doing anything with .plist files. I suggest that if the Logitech keyboard's software included a preference pane in the System Preferences window, you look carefully at all the settings in that prefpane for any that seems like it might have affected the mapping or behavior of your arrow key, and then look in Hard drive/Users/youraccountname/Library/Preferences for a .plist file with Logitech in its name or that appears related to the Logitech keyboard. If you find one, drag it out to the desktop, restart the computer, and see whether the key behaves any better. If you don't find anything in that folder that strikes you as a likely suspect, look for a .plist file with a "last modified" date on or shortly after the date when you first connected the Logitech KB, and drag that file to the desktop, then repeat the test.
Not knowing what if any software was installed to support the Logitech KB, and relying totally on your recollection that the problem began when you first used it, this is about all I can suggest. The ultimate resolution if all else fails will be to reinstall your OS, but I hope if my suggestions fail, someone else will have other ideas for you before you go to that drastic and tedious length.
Of course if you have a bootable clone of your hard drive from before the problem arose, simply restoring that to your internal hard drive will resolve the problem in about the same way as reinstalling everything, but in a small fraction of the time.
Message was edited by: eww