It's a mystery that has perplexed me for months. What IS making my Firefox internet browser crash? Why is Firefox soaking up 90% of my CPU and killing all other programs in the process?

At first I was inclined to blame Firefox as they are the nearest convenient target. But others (especially those on the Firefox user forums) insisted that the problem came from a malfunctioning Firefox extension. The trick was to deactivate them one at a time and see how Firefox reacted. But when this was first suggested to me, I had about 30 extensions and I honestly couldn't be bothered deactivating each one at a time - it was just too time-consuming and tedious a task. Besides I was still convinced it was Firefox's fault that the browser was going crazy.

Then a while back, in an effort to speed up the computer, I stripped down my Firefox browser to the bare minimum with my top ten "must-have" extensions. But still the problem persisted. Within 15 minutes of Firefox being started up, the CPU would hit 100% and Firefox would account for 250,000 k of space. This is a staggering amount for one individual program and it meant that Firefox was accounting for approximately 85% of the CPU usage. In these circumstances, Firefox was totally unusable. So I finally decided to see if one of these ten extensions were to blame and so I began deactivating them one at a time and waiting 24 hours to see if it had any effect.

Initially I suspected the "Customize Google" extension as I have heard some rumblings in the past about its shortcomings. But no, it wasn't that. Deactivating the "Customize Google" extension had no effect on Firefox whatsoever. So the next day I randomly chose another extension in the list, clicked "deactivate" and waited.

Within 10 minutes, the CPU usage for Firefox dropped from 90% to 2% and its total space went from 200,000 k to 95,000 k . 8 hours later, it remained the same.

What was the offending extension that causes Firefox to do a Kamikaze death-dive?

The Skype toolbar for Firefox.