Fairly often when I'm using Firefox I'll suddenly find that the arrow keys have stopped working. I could be typing something in a text box and using the arrow keys to navigate the cursor, or I could be using the arrow keys to scroll a page up / down, or anything else, or trying to arrow down through the menu bar selection. It doesn't matter; the arrow keys are completely ignored everywhere within the Firefox program -- except for one case: If I press and hold an arrow key long enough for the auto-key-repeat to kick in, then the arrow key will be recognized and the appropriate response will be performed -- but only rapid-fire, and only for as long as I hold down the arrow key. When this problem occurs, it's only within Firefox. When I switch over to any other programs that happen to be running, the arrow keys behave normally. The problem happens often, but not necessarily every time I run Firefox.