Hi, I have just the same problem you are experiencing.
I too recently bought a JVC DR-M10S and now every time i turn it ON, it enters in a LOADING state for about 10 to 20 minutes.I can't turn it OFF, EJECT, there's nothing I can do when it gets like this.It interferes with the image quality too(some green lines appear in the screen over the image). I read in some forums it is a common bug with this model. I think I'm going to try to trade it for another model. Have you had any link with the firmware ?