Unable to look to either side while engines running

Does anyone have an idea of how to fix this issue? While I'm "sitting" on the ramp with the engines off, I can pan in any direction I need to; either in virtual cockpit or 2D modes. However, after engine start in any aircraft, whenever I try to pan left or right the view tries to snap back to center like I'm shaking my virtual head. I can pan up and down just fine, but the issue is left or right. I've tried adding a pan command in the FS9.cfg but it's not working for me. Help?!?