1. Libraries and Boards.
Many people install the libraries and 3rd party hardware support in the wrong
place on their hard disks.
libraries should be installed in the Arduino "sketch" folder, and not in the IDE folder,
as per the following page:
How to Install a Library.
You should create a new folder named "..\Arduino\libraries".
That page is linked off of this page:
Getting Started with Arduino.
This way, the libraries and board support will automatically be found when new versions
if the Arduino IDE are installed.
similarly, support files for Arduino board types, other than the standard boards,
should be located in a new folder named "..\Arduino\hardware".