I don't know if this will help, but how are you changing the data location?
I believe it should be Database -> Set Datasource location -> Create New Connection -> ODBC -> Pick your new ODBC name
Also have you tried creating a new Crystal report using the new ODBC link? It could be really noddy, but to prove that it works with Crystal and is pointing where you expect.
Also have you unticked Save Data with Report?
Good luck,
Caspar