I am having this issue as well. FSX, Windows 7 64 Bit. Seems like it is most common when I try to load a cold and start panel state. I can get the engines started, but there is no air pressure once I shut off the APU and advancing the throttles does not do anything, the air pressure reads 0. Switches are in the right positions. Tried the suggestions above, no luck. I've also noticed that with one of the cold and dark configs that the Electrical hydrolic switches don't work, has the overheat light above both the switches. This loads like this by default.