Driving thoughts

Here is an scenario. There are three lanes, A, B and C all in the same direction. Suppose you are driving in lane A. Lane B is empty and lane C has a driver, slightly ahead...

You need to shift to lane B, so you put on your indicator, look back, give it sometime and take all the necessary precautions. Just when you move, driver in lane C decides to come into lane B as well. You are looking back, accelerating slightly (best to increase speed when changing lanes and all that) and don't see the other car until the very last moment.

At this time, the traffic ahead suddenly decides to freeze. (As it does so often on US-101 near Palo Alto, near San Mateo bridge and near Shoreline blvd) . The car ahead slams it's brakes, you slammm your brakes as well (that's slam with three m's). If you rear-end the other car, is it still your fault ? How do insurance companies establish fault in this case ? And, who was really at fault ?

I always thought I was a safe driver, what with the zip-zap-zoom experience of 36 kilometers on my bike in Bangalore city traffic every day sharpening my instincts. (or so I would like to think!)
Inspite of that, I have gotten into close-call situations on multiple occasions, today inclusive, always because of this three lane problem.

What does one do ? I can't not switch, because I need to move from the car pool lane to the exit lane (about 4 in all) in a short span. I dont want to switch well ahead, because the other lanes are soo slow.

What does one do, what ?