I have an Oracle DB where I the user is A_USER and I connect as SYSDBA and have tables under the user SYSADM. I have connect many DBs using ODBC but for some reason ODBC (Win XP Pro) can not connect this one. Any ideas?
Hmmm, you are connecting as A_USER AS SYSDBA, which means you are connecting as SYS and not A_USER, right. Then, the tables are under a 3rd schema called SYSADMIN? Interesting setup.
Have you validated the ODBC software you are using support connecting with the AS SYSDBA option? Some don't.
Does this database have the remote_login_passwordfile=exclusive, and you have used orapwd to create a password file in either the default location or the location specified by registry key ORA_SID_PWFILE? Even if the ODBC software is on the same computer as the database, going through the ODBC stack might make you appear to Oracle as a "remote" or network attached user and thus you're not being authenticated by the operating system (i.e., by your membership in group ORA_DBA) but rather by membership in the password file. And that of course would be the user named A_USER and not your operating system account in some cases, but the opposite in other cases depending on the ODBC driver and whether or not you're viewed as a locally authenticated user or not.