I have a docking station at work that my Air plug into, and a Thunderbolt at home. Since mountain lion install I have irregular boot performance and shut downs. 1 in 3 times that I boot my machine I get stuck at a grey screen and need to perform a safe mode reboot which seems to correct it, or a improper shutdown / request to send information to apple. More specifically I have at work this dock: http://j5create.com/jud500.htm and 2 display link usb to dvi/vga adaptors: http://www.tripplite.com/en/products/model.cfm?txtModelID=3939 This enables me to run 3 external monitors on my 2012 13" 8GB MBA. This works fine when boot issues do not occur, or in safe mode reboot. At home I have a 27" TBD display and one of the same Tripp-Lite USB adaptors enabling 2 external monitors. First question - Does anyone have any suggestions as to what the issue could be? Second Question - Is there harm in booting in safe mode with a MAC? I come from a Windows environment and this is my first MAC so I am uncertain if anything is different with it. Safe Mode reboot in Windows is harmless and has no real long term negative effects, but is that also true of a MAC environment? Third Question - anyone have similar issues with external monitors, docking stations, or just a standard ML configuration?