Hi,

I had the same problem but after I have installed service pack 2 ( SQLServer2005SP2-KB921896-x86-ENU.exe ) problem doesn't exist anymore. Restart pc, be sure that all services are running (look at computer managment/services and applications/sql server 2005 services).

Except sql you have to have oracle net asistent with created net service name. This service name you will use like data source.

Go to sql server managment studio/server objects/right click/new linked server/write name of linked server, make Oracle provider for OLE db/write some name to product name/write the same data source from net assisten from oracle.

Go to security and check "be made using this security context" and write login and password.

Thats all.