It shouldn't do this. I used adaptive cruise on a long trip last weekend, and had it enables for 2 hours, each way, and never had it shut off when switching lanes. At one point, I had to swerve around some road debris, and crossed lanes without a blinker, and it still didn't shut off.

 

The only time it should de-activate is if debris (or bugs) get stuck to the lens. I have a 2011, so no stop-go ACC, so below 15mph it will disengage.

Changing lanes should have no effect on it.

Activating the traction control will disengage it instantly.

 

I wonder what I did to disengage it then. Maybe I tapped the brakes myself unconsciously. I guess that can be crossed off the list for now and I'll make a new thread if I can reproduce an issue.

 

I did a test drive in a 14. If you flip the gimicky selector from drive to park while underway it won't do anything. I let the salesman do it just in case ;-) but it didn't drop the tranny out the bottom like I expected.