Null reference exception creating NT service

[Darren B]

I have some code in C# that works fine running from a windows form. But i
take the same code and run as an NT serivice and I get the following error
'Object reference not set to an instance of an object'.

the line of code is as follows:

message = session.GetMessage(ID,Missing.Value);
where session is an active MAPI session and ID is a valid EntryID.

As stated it works fine when as a windows app and also when I latch onto it
to debug I cannot creat the error. It only happens when it runs as a
service and I capture the error in the event log. The other side affect is
the app grinds to a halt even though all error handling allows for the app
to continue.

Any ideas anyone I am using CDO 1.21