I managed to use the programme for the first time after original install. Next day it just hung on opening with the panels all their on screen but with the splash screen still centre and "not responding" at top of screen. I am totally new to Lightroom and set it up using Scott Kelby's book Lightroom 5 everything appeared to set up properly. I uninstalled the programme and reinstalled exactly same thing has happened. Is their a maximum caralog size that is usuable, mine is 2.7TB and is on one of the desktop's 3 discs.