My HMC150 is doing the same thing. Freezes and have to pull battery out to turn off. Have tried several cards and they all do it. Sometimes it records OK, sometimes just a minute or two and counter for media card stops. Can't turn off unless pull battery out.
I have tried 4 different types. They all do it. Transcend, Panasonic and Sandisk Extreme, and Levar. It will show it is recording, but media card time left will stop counting down after anywhere from 2 minutes to sometimes it runs 60 minutes before freezing. Will not turn off, stop recording unless pull battery.