It is Compiled as a multi-threaded DLL
I checked the Instancing setting, It was set to Multi-Use.

here is how i defined my class,

Define Class ApptBk as Session Olepublic

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I added your set up code,
Set Resource off
Set Exclusive Off
Set Cpdialog Off
Set Deleted On
Set Exact Off
Set Safety Off
Set Reprocess To 2 Seconds


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I also made sure that before all my returns in my functions that I closed all tables and cursors in COM and that I released the comobject after each call in the ASP.NET app.

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It seems that the stablility degradates with time. In our tests...we'll hit it hard for a few minutes with wonderful results....after a few minutes...someone will get the System.MissingMemberException and then others will start getting them.