RPC_E_CALL_REJECTED when accessing Visio from C#

[Walter Quirtmair]

Hi,
we access Visio 2003 from C# and suddenly get COM exceptions
RPC_E_CALL_REJECTED for
some calls to Visio.

The scenario is:
+ A C# WinForms application accesses a running Visio 2003 through Interop
assemblies
+ It fetches QueueMarkerEvent sent from a custom Menu from within Visio
+ On such a event a new Form is opened in the C# application
+ From there Visio is accessed and some calls return this exception, ie. a
call to change Visio.Application.EventsEnabled

This all worked fine with .NET Runtime 1.1 We recently switched to VS.NET
2005 and .NET Runtime 2.0 and now experience these problems.

What can be the reason?
What to do?

Thanks for any help,
Walter