Hello,
Please Ignore the Messages.
The Errors like
IU failed while deploying V because a compatible product could not be found on the system. Please make sure that a compatible Symantec product is installed on the system.
clearly indicates that
"A compatible product was not found."
The Intelligent Updater 20110427-002.v5i64.exe which you had download was meant for Norton as well as Symantec products as shown below:
So, Since you don't have a Norton Product on the machine, the Definitions meant for Norton Products were not Applied as the Intelligent Updater didn't find the Compatible Product (Norton).
And, Yes, ISAuthDLL are the for the Authorized dll files to Install Virus definitions for the Norton 360Hope that Answers!!!!