FSX crashes after switching to APU power

[Steff123 0]

Hello,When I start-up in cold and dark, I start the APU, wait till it's started, and then press the switch that the APU powers the aircraft, as soon as I press that switch, my frame rates drop till 0.1FPS, before it was on 43FPS.I also tried it upon arriving, when I entered the gate after landing and I press the switch, so the APU powers the aircraft, FPS drops till 0.1This only applies when the aircraft is powered by ONLY the battery and then I switch to APU power Re-installed, but no luck Any solutions? And where can I download all the hotfixes? can't find the topicsTried google and avsim forum search, but couldn't find them.