GAEN is general audio error notification. It's supposed to be able to send a message to a person or distribution list when the system encounters an error. However, the 2.4.x version had some problems where it would hog the CPU, so it's recommended it be disabled. Unity 3.x should have a much better implementation of GAEN.
Are you getting this error “Installer User Interface Mode Not Supported. The installer cannot run in this UI mode. To specify the interface mode, use the -i command-line option, followed by the UI mode identifier. The value UI mode identifiers...
The below trick might come handy when you have to add a new node to a cluster but you don't have or is unsure of the security password for the publisher. This procedure has been around for ages.
1) Login into the CLI of the Publisher.