Onsite today, we kept receiving an error from the data_engine when we tried to test the connection to a remote SQL server indicating invalid connection string attribute. SFDC didn't give us much, so googling the error we came across the link below. Just in case you ever run into the same problem, seems like SQL 2005 has issues with remote connections using passwords with any of these symbols: "," "." ";" "["
http://connect.microsoft.com/SQLServer/feedback/details/398243/invalid-connection-string-attribute-error-when-trying-to-connect-to-remote-sql-server-with-a-somewhere-in-password