Macbook hangs at startup I've been having problems occasionally starting my Macbook Pro Retina.  It just hangs on the gray screen with the activity indicator.  When I launch in verbose mode it stops at this line.

AppleUSBMultitouchDriver::checkStatus - received Status Packet, Payload 2: device was reinitialized


How do I determine what's causing the issue?
How long have you left it at that point?  Another user reports the same issue, but they left it for another 15-20 minutes and then another message appeared highlighting a disk failure.

Try creating a bootable back up on an external drive ASAP and test it.  Then at your leisure investigate further, that is leaving it on the start up verbose message screen.

I personally would recommend using carbon copy cloner as it was quite useful, but super duper has a free mode that should work for you.