Hi Dave
Further investigation and it appears to be ACARS setting in advanced settings in option 2. if I enable it I receive the run time error . If I disable it and load FSX again then select flight and finally connect to FSX the message window appears displaying the details, then FSX Kneeboard appears and its ok. It seems that when Acars is enabled in my system that somehow the error window is generated a the same time as the kneeboard window appears when ACARS is disabled?.
Hope this makes sense to you.
Rich.