Error# 20599 may come due to following circumstances -
 The data source is renamed, moved or deleted after creating the recordset or unavailable.
 An ODBC Data Source Name (DSN) is renamed or deleted after creating the recordset.
 A password is required to connect to the original data source.
This problem is most talked about problem and the reasons may be any of these, or may be some other consistency related problems in your database.
Ask your admin. for such consistency checks, due to reason than rename or unavailability of objects may be a prime cause of such error.
- Som Dutt