I just got my PN-40 as well, and you need to upgrade the firmware. I had the exact problems you describe until I loaded the 2.4 firmware (it came with 2.3).
Shortly thereafter I discovered that they have the 2.5 RTM firmware available in their forums.. I loaded that and everything is groovy so far. Here it is.
Edit: <sigh> Looks like the problem wasn't solved. I really don't want to go through returning this thing.