SpaceX scrubs Sunday launch attempt, will likely try again Monday

The weather cooperated just fine on Sunday evening, near sunset in Florida, but the rocket did not. With just 10 seconds to go before liftoff, the on-board computers detected some issue within the rocket's guidance, navigation, and control system. At that point the flight computers stopped the countdown just before the engines were ignited. This forced a 24-hour scrub. If it can diagnose and fix the problem, SpaceX will make a second attempt to launch the Intelsat 35e satellite on Monday, with the launch window opening at, or around, 7:37pm ET. More

(Source: Ars Tehnica - Jul 3)