When you are using Oracle calendar connector and switch from the calendar explorer back to another explorer the Out'n About! menu disapears.
This occurs because Oracle incorrectly deletes all Outlook temporary menus when switching from the calendar explorer. We have notified Oracle and hope they fix this problem in a future release.
If you encounter this problem, please contact Oracle technical support and describe the problem. The Oracle addin corrupts ALL Outlook addins that use temporary menus!