I noticed that Firefox's memory usage would slowly climb until it reached 500 or 600k. I observed that when this happened, the CPU usage would go to 100%, the cursor would freeze or turn to that scrolling blue circle, the screen would white-out a la 'not responding' and the 'EN' (for language) and the arrow to show hidden icons in the notification area would disappear. When it finally unhanged, the screen would flicker, the Firefox icon in the task bar would move outwards then back in (like another program was opened then closed) and the 'EN' and the arrow would re-appear and the CPU usage would drop. The longer Fireofx was left open, the more times it happened (up to several times a minute) and the longer it took to unfreeze. All other programs work perfectly while this is happening.

The only thing that works is restarting the browser but this is not really a solution because the problem just comes back. I often work with many tabs open (sometimes up to 10) but I have noticed that this occurs even when I have only one tab open.