Recently my laptop started exhibiting an annoying problem in Firefox, namely that the page up and page down keys stopped working, and the cursor up/down arrows performed like home/end instead of scrolling. i.e. they went straight to the very top or bottom of the page.
After verifying that the problem didn't happen in Internet Explorer, I finally tracked down the problem to something called "caret browsing" being turned on in Firefox. This is a mode I'd never heard of, used for accessibilty on web pages. Basically, it allows the user to jump between links on a page. To disable it all that was needed was to press the F7 key - such a simple solution to something that had been bugging me for two days!
