Another head-scratcher –
I just did an upgrade for a client who went from v10.0 to GP2013 (in-place upgrade; no server move). Two of the PCs were brand-new, so didn't have pre-existing ODBC connections to the server. On the other three workstations, we did not change/modify their pre-existing ODBC connections in any way. The pre-existing ODBCs are using the server name, as opposed to using the IP address. They may also be using a different version driver; we didn’t think to check at the time.
The new PCs are using the IP address to connect, and they are using the SQL Native Client 10.0 driver. (SQL version is SQL 2008 R2)
On a pre-existing computer, I have a user who can log in as himself, successfully, and use DGP. On the new PC, he cannot log in as himself – he gets the typical “login failed, contact your admin” message. He definitely, absolutely logged in with the correct name & password, and he used the correct case, i.e. Capital letters. The user to whom this PC belonged also could not log in, so I went in as the ‘sa,’ reset her password, and then she could log in.
Have you ever seen that, and what do you make of that?