Hello zeddartha,
Hum… not sure what’s happening for you there
I’m also using an Intuos4, so can’t reproduce your hardware setup.
But, do you have Snap To Grid enabled in AR's Layout Panel? Maybe you could post a screenshot of what settings you have in there.
As I can sort of reproduce what you are getting at different zoom levels if I monkey around with a combination of settings in there + canvas size.
Also;
Which tool are you using. Pencil, Ink Pen or Custom Brush?
What size is your Canvas ie. H x W in pixels?
What OS are you on?
Do you have the latest Wacom driver; Mac 6.3.38-3 & Win 6.3.38-2