Indeed Staggy Stagg, what you have described happened to me twice, below is a snapshot of one of them:
Click image for larger version.  Name: Error.PNG  Views: 73  Size: 72.0 KB  ID: 33020

And the player i sold looks like this:
Click image for larger version.  Name: Player.jpg  Views: 73  Size: 49.3 KB  ID: 33021

This happened to me 2 times, and the only link between the 2 cases is that I tried to sell the 2 players many time, over and over, and 1 day they were sold to these "Ghost teams".

@ Staggy Stagg: How many times you were trying to sell your player?