I 'm posting this because I have run across some weird behavior that was causing calibration problems with my QHY 163M. Since there are numerous threads on calibration problems with the ASI 1600mm which has the same chip, I was wondering if there might be some correlation. The software I'm using is CCDAP, Foocusmax V4, The SkyX CAO, and the ASCOM driver for the QHY 163M. The problem occurs when I begin an imaging run in CCDAP by focusing in Focusmax. After the focus run there is an approximately 3500 ADU pedestal added to all the subsequent images. This isn't a terrible problem by itself, however if I close everything after the run and then restart it at a later time to take calibration frames without using Focusmax then the pedestal isn't added to the calibration frames and the calibration frames fail. If I take the calibration frames immediately after the imaging run without shutting anything down then the pedestal is added and the calibration frames work fine. This was driving me nuts until I figured it out. Whether this has implications beyond my own particular setup I have no idea but I thought I would put it out there for someone who may be running into calibration problems to see if it might relate to what they are experiencing.