Connecting via SQLServer?

[Blink]

We have an ASP.NET application running on one machine, and a SQL Server on
the other. Under development conditions the application runs fine, and can
connect away to its heart's content, but when we deploy it we get connection
issues. The exact error message we get is

"SQL Server does not exist or access
denied....System.Data.SqlClient.SqlException: SQL Server does not exist or
access denied. at System.Data.SqlClient.SqlConnection.Open() at
Microsoft.ApplicationBlocks.Data.SqlHelper.ExecuteDataset(String
connectionString, CommandType commandType, String commandText,
SqlParameter[] commandParameters) in
c:\inetpub\wwwroot\testdb\sqlhelper.cs:line 424 at
Microsoft.ApplicationBlocks.Data.SqlHelper.ExecuteDataset(String
connectionString, CommandType commandType, String commandText) in
c:\inetpub\wwwroot\testdb\sqlhelper.cs:line 403 at
testdb.testdb.Page_Load(Object sender, EventArgs e) in
c:\inetpub\wwwroot\testdb\testdb.aspx.cs:line "

Has anyone seen this before? We know the connection string is correct, and
that the server exists. The machines can ping each other. Does ASP.NET need
to be given special data rights or anything like that? Do I need to set up a
trusted connection between the two machines? Any help would be greatly
appreciated.