Comment 10 for bug 1379702

I also just experienced a similar crash. When I turned off my second LCD connected via DVI:

The program 'xfsettingsd' received an X Window System error.
This probably reflects a bug in the program.
The error was 'BadRRCrtc (invalid Crtc parameter)'.
  (Details: serial 2320 error_code 148 request_code 140 minor_code 21)
  (Note to programmers: normally, X errors are reported asynchronously;
   that is, you will receive the error a while after causing it.
   To debug your program, run it with the --sync command line
   option to change this behavior. You can then get a meaningful
   backtrace from your debugger if you break on the gdk_x_error() function.)