Today my Keurig completely stopped working.

I called their customer service number (excellent service by the way) and through a process of elimination we discovered that because I had been using very cold bottled water straight from the refrigerator it would cause the machine to lock up. The customer service rep talked me through running a couple rounds of room temperature water through the Keurig and it started working right away. Now it's back to normal!
Thought everyone might like to know to not use refrigerated water.