I don't see too many MC XL CEREC tower communication glitches.  But it did happen today with the last patient of the day!  I heard the milling unit spinning without the familiar bur-on-porcelain sound.  I have experienced this more since going to RF connection from WiFi.  Fortunately, I have a second milling unit and proceeded with a normal mill while the first milling unit struggled. After 30 minutes we aborted the mill.  So what is the solution if your office only has one milling unit when communicational glitch occur?