I'll second contacting the developer but don't hold your breath for a reply. I've given up on Ripit. It used to be great with an active community with lots of back and forth between users and the developer (I've recommended it to many people) but sadly the community forum has been disbanded and the software itself hasn't been updated in years (the latest version - 1.6.6 - was released back in mid 2012).
Many people have contacted the developer as ver 1.6.6 was having issues with more and more content, but nothing has been done. I have a suspicion that it's been abandoned, although the product is still being sold.
Alex from thelittleappfactory.com (yes they still seem to be active) emailed saying
'Your Mac is going to sleep while ripping. Go to 'System Prefs>Energy Saver>Computer Sleep' and make sure it is turned to 'Never' while ripping to ensure that this does not occur.'
I am surprised that I had never ripped a dvd before and discovered this. I am also surprised that Ripit doesn't function like other programmes and keep the mac awake. However.
Int he meantime I had been forced to go back to MacTheRipper on an old machine. It is a great shame that none has been able to maintain this programme which is excellent.