We recently experienced an issue with a Linked Server, to an AS400, which would periodically stop working with the error:
"SQL State: 4, SQL Error Code: 7340, Level: 16, Procedure: , Line: 1 Cannot create a column accessor for OLE DB provider "IBMDASQL" for linked server"
The Linked Server connection would be fixed by:
1. In SSMS go into the linked server's properties and then press OK.
2. Programmatically by executing a stored procedure: exec sp_enum_oledb_providers
Do not know why this occurs but issue seems to be with provider IBMDASQL.