Guild Wars 2

At the weekend had problems with sound in the game. Sounds and music are late for in-game events for 5 to 7 seconds. Part of the sounds altogether disappeared.
Please tell me what’s wrong.

This quest consists of four parts.
The problems begin with the third part. The task you need to kill Teyo and pick up the artifact. But the murder Teyo not counted and not the next phase of the assignment!
Please fix this, because by it I can’t go on my personal story