ADODB.Recordset and VFPOLEDB.

At times we get this error:
OLE IDispatch exception code 0 from Microsoft Cursor Engine: Multiple-step operation generated errors. Check each status value...
I believe "exception code 0" is from VFPLOEDB.

Each time we get an error, the query is logged in the error log.
Later in the evening we can test exactly the same queries, and they always work just fine.

What is "exception code 0" ?
Can someone point me to where this is documented?