I haven't used my 3DS so much, so it's annoying to see a problem on it like this. On the touch screen, I get a permanent vertical black bar, about one pixel wide, a bit offf-center to the left. I'm pretty sure nothing can be done about it, but I decided to write just in case. (When the screen goes black, the bar sometimes gets white a moment, just to be contrary...
It out of warranty, as I had it a while, but again, I barely used it, so it's not that old.