SimConnect.dll_unloaded error

I'm having this problem since SP1b. FSX exits with this error message when i'm enroute and switch from full screen to windowed to check for wheather condition at arrival airport. However, it has become worse. I have it also at the 4% mark of the FSX loading bar where it loads gauges. I tried everything possible to resolve this, lowering graphics and such. As said, with SP1 no problems at all, with higher graphic settings. I'm looking forward to the SP1c and hope the problem will vanish because i trashed the SP1 when the 1b was released.Regards,