I have a Visual Basic application that executes a Baan DLL function, which in turn runs a Baan session. If I do not already have the Baan client open, it works perfectly. If the Baan client is already running, it works but gives the following BW error message twice:
Object 0 in process <session PID> not found

I tried one of the Baan sample spreadsheets, and the Baan sample works in both cases without error. The error messages appear during the execution of the Baan session, somewhere between the before.program section, and the form.1/init.form section.

Sample pseudocode:
[Windows application]
BaanObj = CreateObject("Baan4.Application")
BaanObj.ParseExecFunction <DLL>, <DLL function>

[Baan DLL function]
change user's company according to argument passed to the DLL
activate("<Baan session>", <arg1>)

[Baan session]
nothing special going on here

Try replacing activate with zoom.to$ in Baan IV or start.session in BaanERP.