Customers generally get upset with companies if they broke a promise or have a broken process. So to avoid a catastrophe you must stay on top of those two things.
To continue to to live up to your promises you must be Open, Honest, Real & Love your customers. The last one may seem like a stretch, but customers want to feel like there is a real person helping them out, someone who cares. Be a little loose, show some humanity and use humor, while maintaining professional boundaries.
Abby Johnson of Web Pro News interviews Rob LaGesse of Rackspace Hosting as he explains how he has managed and tries to prevent large scale Social Media catastrophes.