We are getting an error in our system which recurs frequently but not predictably. The unpredictable nature of the error is making it difficult to find the root of the problem.

The system consists of:
VB6 front end running on NT client
Uses approx 7 client-side COM DLLs.
These use 1 MTS component (which basically wrappers ADO calls) on NT Server
This connects to SQL Server 6.5 database (not necessarily on the same NT Server) and returns disconnected recordsets to the client (some can be very large - up to 60 MG)

The error is:
"-2147467259 The data provider or other service returned an E_FAIL status."
(We think it might be raised in Microsoft Cursor Engine originally.)
It never occurs in the same piece of code which is why we are looking at the system architecture.

We have tried altering client PC/Server combinations to see if disk space/network traffic/memory is causing a problem but have not found a pattern. Searches on MSDN have also not provided us with any useful leads.

Does anyone have any ideas?
Janet