U.S. court orders Symantec to pay $17 mln for patent infringement

The plaintiff was Intellectual Ventures, the giant "Non-practicing Entity" founded by Microsoft Millionaire Nathan Mhyrvold. I.V. had apparently purchased the patents in question, not even inventing them itself.

It's not relevant to infringement, but what was the nominally infringed-upon idea? What did Symantec do to infringe? Did Symantec invent this "I.P." independently or actually rip off I.V.? That would also be a first, probably.