> The invalid transaction handle exception goes like this (the second
> exception happens immediately after first, while the third is during
> shutdown of Project12.exe):
>
> First exception:
>
> Project Project12.exe raised exception class EIBO_ISCError with
> message 'ISC ERROR CODE:335544569
>
> ISC ERROR MESSAGE:
> Dynamic SQL Error
> SQL error code = -901
> invalid transaction handle (expecting explicit transaction start)
>
> STATEMENT:
> TIBOInternalDataset: "<TApplication>.Form1.<TXtrimDataSetModule>.tblW
> ebUser.<TIBOInternalDataset>'.
>
>
> Second exception:
>
> Project Project12.exe raised exception class EIB_ISCError with
> message 'ISC ERROR CODE:335544727
>
> ISC ERROR MESSAGE:
> unassigned code
>
>
> Third exception:
>
> Project Project12.exe raised exception class Exception with
> message 'This is a potential problem: 335544332'
>
>
> Assigning IB_Session explicitly doesn't seem to help...
> By the way, does IBO allow creation of IB_Session during run-time?

yes it does,
but I see above that you have a form involved. what role does this form play
in your threaded activities?
You know the VCL is not thread safe don't you.
Alan