Microsoft.Jet.OLEDB.4.0 - Error

Hi,

I am using SQL Server 2005 (SP1) on Windows Server 2003 EE (SP1).
I get following error while accessing Excel or Text file data sources with
OPENROWSET or OpenDataSource and Microsoft.Jet.OLEDB.4.0:

From SQLAgent Job Log file:
Cannot initialize the data source object of OLE DB provider
"Microsoft.Jet.OLEDB.4.0" for linked server "(null)". [SQLSTATE 42000]
(Error 7303) OLE DB provider "Microsoft.Jet.OLEDB.4.0" for linked server
"(null)" returned message "Unspecified error". [SQLSTATE 01000] (Error 7412)


From SQL Server Management Studio:
OLE DB provider "Microsoft.Jet.OLEDB.4.0" for linked server "(null)"
returned message "Unspecified error".
Msg 7303, Level 16, State 1, Line 1
Cannot initialize the data source object of OLE DB provider
"Microsoft.Jet.OLEDB.4.0" for linked server "(null)".


All this works fine on:
- SQL Server 2000, Windows Server 2003 EE
- SQL Server 2000, Windows XP Professional (SP2)
- SQL Server 2005, Windows XP Professional (SP2)

What is more it worked fine in my current configuration i.e. SQL Server
2005 (SP1) on Windows Server 2003 (SP1) until recent restart. No updates
were instaled during restart! This was just because of some expected power
cut off.

SQL Server service is running as Domain Admin.
Domain Admin is logged to the server.
I am trying to execute the query as Domain Admin and Local Admin.
EVERYONE has full rights to the file I want to access.

SQL Server "Ad Hoc Distributed Queries" option is set to 1
DisallowAdHocAccess registry entry is set to 0


NO MORE IDEAS!!!

Does Anyone know the solution?

Regards,
Grzegorz Niemiec