When you create a new session in TOAD, if you inadvertently have “Sysdba” selected in the “Connect as:” drop down, and you have dba authority on the DB, TOAD will connect you as “SYSTEM”, but display the value in the “User / Schema” dialog box in the connection string tabs.
This is totally misleading, TOAD should display “SYSTEM”, not the account. I encounter it when I open the connection dialog. The previous connection is displayed, I update the User / Schema and password fields, but forget to change “Connect as” to normal. TOAD logs me as as “SYSTEM”, but displays the account I just entered in the User / Schema text field.
This led to 30 minutes of wasted time yesterday when I attempted to fix a DBLINK, but the programmer using it complained it was still broken. My tests showed it was good. Only after much gnashing of teeth did I discover I was logged in as SYSTEM, not the account displayed on the session tab.