I just installed Oracle10g Express on Linux FC6.

I get errors in Java and SQLPlus when trying to connect to the database, or start it.

In SQLPlus as "sysdba" when I type "startup" I get this error...
ORA-27100: shared memory realm already exists

And in Java or SQLPlus when I try to connect as a valid user I get this error...
ORA-01034: ORACLE not available
ORA-27123: unable to attach to shared memory segment

Please help me.