Are you on a 64bit Operating system? If yes, then on your lab machine you would have both 32bit and 64bit versions of ODBC DataSource administrators.
They are:
C:\Windows\SysWOW64\ODBCAD32.exe
C:\Windows\System32\ODBCAD32.exe
Since you created a DSN to Access 2003, then am sure the DSN would be 32bit, and you would need to open the ODBC data source administrator from the following location: C:\Windows\SysWOW64\ODBCAD32.exe
(Office 2003 editions)Access 2003, we only have 32 bit edition, and the DSN would be 32 bit by itself.
Hope this helps..
Chaitanya (http://twitter.com/chmediko)