I have created a COM object (called exporter) which includes an export method. This method can take several mins to run.

Say a client program does this:
ox = CREATEOBJECT("exporter")
ox.Export()
The client has to wait until the export method finishes.

Instead I put a timer into my COM object (which is based on a Form class). The Export method just enables the timer and ends. When the timer fires it runs the 'real' method (now called do_export).
This gives me asynchronous control and works really well. If the client wants to check progress in the COM object it has properties such as PercentDone and Busy etc.

The bad news - the error handling fails if a timer is used. Instead of my Error method kicking in with my COMReturnError message I get:
Fatal error: Exception code=C00000FD every time.

If I call my method directly - error handling is as advertised - indirect it via a timer - Fatal Error.

Any suggestions - or alternative approaches to the problem?
Many thanks
David