Hi, haven't had this problem with our new TCH, but I have a 2003 (gas-hogging, nonhybrid) Highlander with a 6CD changer.

After a while, some of the frequently-used buttons started sticking in. In my case, it's AM and FM. If one of these buttons is stuck, the radio will stubbornly refuse to do anything I ask it to. The first time, it took me quite a while to figure out. The buttons on our 2007 TCH radio/CD are different from the Highlander, and I don't know whether the same thing can happen. Thought I would mention it.