I use a Zoom H4n to record MP3's for my companies clients to later have transcribed. We picked up the Zoom recorder about three months ago and have had great experiences with it thus far. Yesterday while on a shoot, the zoom froze at the start up menu after a half day of being use. I tried hard start it and power it using the AC cable, frozen, then I tried to use new batteries, still frozen.
The weird part is when I connect it to my macbook via USB can control it but as soon as I disconnect it becomes frozen at the start up again. As far as I know I'm at software version 1.72 the most up to date.