I was locked out of my mac for 2 days. I figured it out and wanted to post my solution so others could benefit.
In the past, I have paired my wireless keyboard to my iPad2. So two days ago a when I shut down my Mac mini to move it to a new location my iPad took the opportunity to pair with the keyboard. The keyboard can't connect to more than one device at a time. So while it's connected to the iPad the Mac mini waited for it to be free. Simple solution, instructed my iPad to forget the device and the Mac mini paired instantly and I was back up and running. I'm probably not the only one who's run into this but I'm probably the only one that took 2 days to recognize the solution. Doh!