#2. "RE: D5100 malfunctioning - black rectangle appears in photos" In response to In response to 1
My friend was using it when this started, he says he was using primarily the portrait mode, but it happens in all. Flash was on yes, but the shutter speeds were just presets - nothing fancy. Flash off also does this.
Here is a link to an example of the problem. Seems the top corners are also rounded off. It looks like something has just slipped but not that I can see.