Hi Mike,
I have to say, it is normal. 120 is our first generation of product, So it has many problems.
For your problem, I think it should be caused by Snap. We know the snap mode for 120 has problem, but it is limited by the hardware, we could not solve it now.
So I think you should use video mode to avoid this problem, only for 120MM and 120MC.
You can use this sentence to check:
if (CamInfo.bIsUSB3Cam || (CamInfo.Name.ToLower().IndexOf("mini") > -1))
ASICameraDll2.ASIStartExposure(CamInfo.CameraID);
else
ASICameraDll2.ASIStartVideoCapture(CamInfo.CameraID);
Thanks
Chad