Merge your ~/.Xauthority with the ~/.Xauthority of root:

sudo xauth merge ~user/.Xauthority

Or for a more permanent solution:

1. Modify your ~/.bashrc to contain the following:

   export XAUTHORITY=~/.Xauthority
   	    

2. Modify your /etc/sudoers to contain the following:

   Defaults env_keep += "DISPLAY XAUTHORITY"