After reaching the Symantec Protection Engine Graphical User Interface login page, entering the correct password followed by clicking "login"  continuously produces an error.  The error reports that Protection Engine could be offline, or the password is incorrect.

"Incorrect password or service is not running"

This could potentially be caused by the Symantec Protection Engine SSL port being blocked or not accessible.  The default admin port Protection Engine uses is 8004, and the default SSL port used is 8005.  Both are configurable.  Even though the admin can get to the Protection Engine login page, when the password is entered and the login button is clicked, the SSL port is used to complete the login process.

Please confirm that the client can access the configured Protection Engine ports: 8004 and 8005.  Potentially a firewall could be blocking this port, or another process could be using this SSL port. 

Please also refer to following article:

Page can not be displayed after upgrading to Protection Engine (SPE) 7.8

http://www.symantec.com/docs/TECH236688