>> I went down to the start button and then clicked on Home Selector to make sure 11g was my Oracle home but it said only one client was installed and didn't give me the option to switch.
This would be a good time to put down the GUI and eamine the TNS component files at the OS level!
Here are the steps that I use to debug connection issues:http://www.dba-oracle.com/t_troubleshootin...vity_errors.htm
In your case, the problem occurs because your default $ORACLE_SID is not found in your tnsnames,ora file.
root> set ORACLE_SID=mysid
root> export ORACLE_SID
root> tnsping mysid