Urgent - How dare you delete my tabs without warning?

I restarted Firefox today to find you have removed all my 100+ tabs, which I had arranged in folders, and replaced the vertical settings I had with Tree Style Tabs, which in the past has always run slow. I was greeted with childish graphics inviting me to set up a profile and offering me an introduction to Firefox. I have been using Firefox for years, mostly happily, until you screw up the view I had spent hours setting up. You are turning into a cheap Microsoft but with even less consideration for your users. Will you correct this or do I need to search for a new browser? Francis Shennan, LL.B Writer, journalist and law lecturer.