Sounds like a real head banger. I'll just through this out. Draw your bow and get all lined up without putting your finger on the triger. While looking place your finger on and off the triger. My site window changes when I am not carefull and can throw the arrow off 2" to the right and as you might expect it wasn't always a consistant 2". You could be causing it from the moment you hit the release. I would find it hard to believe you were doing it on every shot though. Hope you figure it out and let us know.

One guy in the past here had a problem he determined to be his axel pins.