Jeyl said:Well, I guess it all boils down to one's interpretation on 'why' the Star Destroyer was just standing there in the first place. When the commander is informed that the rebel ships are trying to escape, he didn't say "Arm the turbo lasers and prepare to destroy them!", he said "Good, our first catch of the day". And since the Star Destroyer wasn't shooting at them, it's a pretty logical conclusion that they were planning on capturing the ships with their tractor beams. Kind of like how the Star Destroyer at the end of the movie wasn't firing on the Falcon when it was getting it's Tractor Beam ready.
The same reason that Tie fighters are firing at the falcon. Its all about disabling the ship(s). like the Tantive thing.
-Angel