I'm getting an exception raise when I use a COM object built with Delphi within C#. The exception number is 0x80040202, which occurs when more than one event handler is assigned. There are three events, the first event handler assigned works fine however the afore mentioned exception occurs when the second event handler is assigned. I've read some stuff from the Microsoft knowledge base regarding a problem with sinker help classes that have the wrong protection type in the Interop type library that .Net generates, but this doesn't seem to be the problem in this case. Microsoft have taken a look at this problem on our behalf and have not been able to find a solution, they suggested it was a problem with the interface within Delphi and suggested we contacted Borland. My development teams next step is to be build a series of dummy COM objects under different languages that use the same interface to try and issolate where the problem is. If anybody out there can sched more light on this it would be greatly appreciated. We don't fancy having to recode all the Delphi stuff in C# just to get round this problem but that's our choice of last resort. Many thanks,