I had the same problem but pivotanimation itself has no vírus, I also used norton while downloading the installer but I ignored norton and decided to install. If you check the pastes where pivot is installed, you'll see there is no virus. It IS wierd.
Once upon a time in the old shabby home by the forest, there was a man named Jim. This young fellow didn't know what the outside world looked like. His Basement resembled a very aged cave inhabited by the creatures called 'Garapata'. The Garapatas were very kind to Jim for they believe that he was a very special kind of warrior, destined to free them from exile. But Jim had other plans in mind. He was going to escape that forest, in case of the long foretold rebellion led by the dirty Drift. This story troubled young Jim, as he wasn't ready for this undertaking, neither were the Garapatas but he realized he had to continue on his journey to kill Drift and perhaps, if fortune held, help free the Garapatas from their exile. But standing between young Jim and Drift was an impassable ridge which resembled death itself. It had eyes and a gaping maw along its cavernous enclosure. The only way to cross was to find and combine the penises they possess. One by one they lined up to donate their penises with hopes that it would help them cross the ridge. But alas the Garapatas had very small penises. Their penis chi was not great enough to erect the bridge they were planning