I got a new mission called "Intercept Course" from the Republic fleet, which directed me to see NPC P-3DB in the hangar of the Gav Daragon. When I went there the location is un-accessible. Has anyone else run into this problem, and how were you able to complete this mission? Thanks

Reset this mission. Go back to your ship. Fly to a different planet. Fly back to Coruscant. For some reason, getting to Coruscant by any other mean than your ship doesn't trigger the mission completion for this part. Easy fix though. Good luck.