I recently ran into an issue (again) where I was running the Java version of Oracle Enterprise Manager (OEM) 10g to manager my Oracle Databases under Vista Business 64-bit. Oracle OEM wasn't retaining my database tree settings. I would delete an old database and add a new one only to find out after I restarted the app that my changes were not retained/saved. With the help of the MS Sysinternals utility called Process Monitor I was able to track down where these database preferences gets saved to. Turns out that they are in $ORACLE_HOME\sysman\config\pref\dbastudio-%USERNAME%.crd. After tweaking the security permissions (taking ownership and allowing my account 'full access') OEM returned to normal saving operation.