This has now happened twice to me:

I suddenly noticed that I couldn't type normally on my N800. It became obvious that, for example, when I would try to type the J key, the g key would be activated. In other words, things were way out of calibration. But I couldn't finish the calibration test if I followed instructions, because the instructions would tell me I wasn't hitting within the range of the point when I was.

So, for awhile I learned to type L when I wanted J, P when I wanted I, etc.

But after a couple days, the problem completely went away!

When this happened the first time, I theorized that I had somehow let a drop of water fall inside the case when changing batteries, and that the problem went away after the drop evaporated. However, this time I am sure I did not open the case before this problem happened, and it's not like I am constantly showering the N800 with water droplets anyway.

My latet theory is that this was due to pressure put on the N800, or maybe overheating?

What could cause keyboard and other screen input to be laterally distorted, a condition that would "heal" in a day or so? The healing process can be detected, as when you type, you notice that you are only a character away from the one you want, then less, then everything is right again?

By the way, the problem was worst toward the right side of the virtual keyboard, which reminded me of the complaints some have had about screen sensitivity toward the right side.

As I say, everything is fine now, which makes this a happier mystery to me. The two times it happened were a month or so apart. I have had my N800 since mid-January and use it constantly.