This IA fight is the most difficult in the game - it's way harder than the ones at the end of chapter 2/3.
Most of the tips have been given, LOS, interrupt etc. Running around and around the computer terminals on the right is usually best for this.
Bear in mind that you have to beat him down 3 times i.e. don't panic after you win once and think it's all gone wrong.
here is his entry at Torhead http://www.torhead.com/npc/6Zz1Hts/darth-jadus which will show you the importance of dealing with his Affliction/Thundering Blast - there are quite a few tips in the comments section.
If you are still having problems I would recommend asking a guildmate to help you out. I know it feels like you are failing if you do this, but frankly you are not being helped by the bug that you can't attack DJ unless you are standing right next to him.
This bug was highlighted (and complained about) well over a month ago when we were still in Beta and still isn't fixed. Well done Bioware - brilliant service.