Just a heads up to Firefox users.
If you like to use arrow and cursor keys to move around webpages, Firefox has by default under Tools, options, Advanced enabled the following setting:
Always use cursor keys to navigate within pages.
If this is on, your cursor jumps throughout the text of the page, similar to a word processor. Fine if not using columns, tables, or the like. But try it on other pages, such as this forum
Simple solution: just clear this checkbox and it will work as expected. Up arrows move up, down moves down, etc.
I was surprised when I found this was set as the default and hope this helps others avoid the problem.