Barometric pressure jumps at FS loading scenery during long flight

Got this problem like this: long range flight, cover several time zones. During flight, the FS will automatically load new scenery and other files with a progress bar when I am far away the departure airport. After the loading, I can see the altimeter and IAS jumped! Obviously the FS set a new weather parameters(temp and barometric pressure I think) during the loading. changes are so sudden and abrupt that the VNAV mode can not sustain and disengage right away.My friends with almost the same FS and Add-Ons installed dont have this problem. Any body has some idear or a solution to prevent this? This is confusing because only after the auto loading will result in this problem. My condition: Vista Utimate+FS9.1+Active Sky 6.5(default setting)+fsuipc(3.85 defual setting but smooth wind)+FSINN(WX update inhibited).