Now that it's been established that your issue is rooted in something in your home folder you can try moving Numbers related items other than .plists to your desktop, one at a time, to see if you can zero in on its source. (I'd restart after each move although logging out/in will probably suffice.)
The new Great Equalizer is the SEND button.
In Memory of Harv: Those who can make you believe absurdities can make you commit atrocities. ~Voltaire
