Mouse Pan Issue

I’ve recently come back to Blender modeling and I am having a little issue with panning and orbiting using my middle mouse button. Most of the time I hold down a SHIFT key and my middle mouse button and can pan my view without issue. But every 10th or so attempt, it rotates my view instead of panning, like I wasn’t holding the SHIFT key. This is in Blender 2.79. Is this a known issue or a problem with my particular set of hardware.