I'm creating a quest where the player enters a trigger and an NPC spawns and force greets the player into a conversation, says one line and then attacks him.

The thing is, it doesn't go into that sort of conversation where the player controls are disabled and camera focuses on NPC and etc. etc. The NPC just stands there and says the line and thats that.

I have temporarily fixed this problem though but only temporarily. If I re-create the dialogue branch and topic in the dialogue view in the quest object and leave the "goodbye" checkbox unticked then it works just fine. But as soon as I tick that goodbye box it will stop functioning and even after I untick it, it will still refuse to function until I recreate the entire dialogue branch & topic.

What could possibly be wrong?

Alright now the dialogue box does not get "corrupted" or whatever, now if I leave the "goodbye" tickbox ticked then the NPC will not engage in the type of conversation that I want, he just stands there and says it and doesn't force the player into a "focused" conversation.

This could solve it: http://www.gamesas.com/topic/1417941-dialoguequest-bug-solution
Just guessing though because I don't really know.

Try setting the dialogue topic to Blocked.