I recently purchased the new Mac Pro and am wanting to use my 27in Mid 2011 iMac as the display screen for it. I have followed all of the instructions here (http://support.apple.com/kb/HT3924?viewlocale=en_US&locale=en_US) but when I click the command + F2 button, the screen turns black for a split second (as it enters the new display mode) after that I get a grey screen with a mouse cursor in the top right hand corner which I am unable to move. Since this is the first time setting up my New Mac Pro I thought there may have been a problem with the nMP, so I tried it on my friends iMac (2013) and it connected perfectly. Has anyone ever come across this grey screen issue before? Any ideas on how to fix it?