I've been having the same problem for a couple weeks now, and I finally figured out what was causing it -- it's actually a pretty simple fix. Rebooting would generally fix the problem, so that's what I've been doing for weeks now. There have been days I've rebooted several times. How I found it: Today, after unsuccessfully trying to connect via USB, I shut the n810 down, and tried to pull out my flash card. Normally, to remove the external flash card, I push the card in, then the spring pops it out. This time it wouldn't pop out. I poked around, and finally got it to remove, then carefully pushed it back it. The spring engaged this time and it seated properly. Root Cause: The external (micro SD card in a mini SD-converter) card had been unseated for some time. Due to the design of the slot, the door, which is normally held closed by its own latch, and double-latched by the stand, mostly holds the card in place, even when it's not seated properly. That means it works most of the time, but is subject to shifting when it's jostled. I fixed mine (at least temporarily) by removing and then carefully reinserting the SD card so that it seated properly. I don't yet know whether I had inserted it improperly in the first place, or whether it worked itself loose during normal usage. I'll pay attention, and post updates to this thread if I find out anything useful. It's working for now - I'll have to see whether the fix holds up, but I'm pretty confident this is what's been causing my problems. I think the card slot is poorly designed, but now that I understand what's happening, I'll be able to fix it faster next time. I hope this helps you all who are having similar problems. David