Excellent suggestions everyone, thank you. I'll try this out tonight when I'm near my PC with the USB cable.

FWIW, I normally have to power cycle the N810 before plugging in the USB cable because I'm using swap space on /media/mmc2 and it's in use according to "load-applet" showing a floppy disk icon in the memory usage bar graph.

When I plugged the USB cable in the last time I got the typical error message about not being able to use the memory card, so I closed all open apps to see if that would close up the swap space. Nope, just one bar with a floppy icon which I assume means swap file is still in use. I figured what the heck, try the USB connection again and this time it mounted without any error message. I get the impression that this is a VERY BAD IDEA from your messages.

Also FWIW, I've been having fun attempting to get videos running on the N810 and I've been filling my 2GB internal card quite a bit. df -h shows 289MB free space right now on mmc2, so I may not be getting to an incorrectly reported limit, but I'd imagine there also could be some fragmentation issues. A reformat also sounds like a very good idea. Is there a preferred formating tool that I should use? Feel free to suggest CLI tools too.