I've been using my mid 2009 15" macbook prro with a 20" apple cinema display for the last year and a half with no problems, until the other day I upgrade to Lion and notice these problems when starting up the computer - connected to the display - and being completely frozen on the login screen.
I assume this is a Lion thing, I can't think of anything else. I have no externals hard drives or devices plugged in at start up. This is a ery annoying problem.
Please any others of you out there experiencing this problem, let me know if you've had any success.
Pro, Mac OS X (10.7.2), 20" LED Apple Cinema Display