Please Verify that the Notifications are set up properly for the Unmanaged dector.
To set notifications when using the "Unmanaged Detector" feature in the SEPM
Open and login to the Symantec Endpoint Protection Manager
Click on Monitors Tab
Click on Notifications
Click on Notification Conditions
Click on Add
Select Unmanaged computers
Correctly-configured notifications should then write events to the database, send notifiation by mail, or perform any other action configured. These notifications can be acknowledged in the SEPM.
Also what is the size for the SEP install in add remove program?