Mash try these steps:
- Make sure that you are using the latest SQL Server
service pack available.
- Check that the client and server are running the same
network protocol. For example, if the client tries to
connect to SQL Server using IPX/SPX protocol, and the
server only has TCP/IP protocol installed, the client will
not be able to establish a connection.
- Verify that the client and server are using the same Net-
Library. The client connected to SQL Server 2000 must use
a client Net-Library that matches one of the server Net-
Libraries to which the server is currently listening. For
example, if the client tries to connect to SQL Server
using Multiprotocol Net-Library, the server should
currently be listening on Multiprotocol Net-Library too.
You can change the client Net-Library by using the SQL
Server Client Network Utility in the Microsoft SQL Server
program group. To change the server Net-Library, use the
Server Network Utility in the Microsoft SQL Server program
group. Note - Keep in mind, any changes made in the
Server Network Utility will be saved, but they will not
take effect until the SQL Server service is restarted.
- If you cannot connect using Windows Authentication,
ensure that SQL Server is not installed on a Windows 9x
box. Windows Authentication is not supported for SQL
Server installed on a Windows 9x box.
- Confirm that the 'single user' database option is turned
off. If you get an error message indicating that the
database is already open and can only have one user at a
time, the 'single user' database option is turned on. See
your database administrator to set this option to off if
several users connect to this database at the same time.
- Check that the 'DBO use only' database option is turned
off. If an error message indicates that only the owner
can access the database, the 'DBO use only' database
option is turned on. Have the database administrator set
this option to off if others besides the database owner
can access the database.

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