Trying to book a very simple multicity (3) domestic ticket. It would let me get to the third leg, then tell me it couldn't book it, and bounce me to the start again. Then, it completely locked up and started giving me that highly annoying, cutesy 'we're experiencing turbulence' message . Just to add to my frustration, I check my email and see DL telling me to go to dl.com for 'stress-free' ticketing. I did make my ticketing experience 'stress-free'...by booking the ticket an another airline's website.