the fault is in Adobe Acrobat. update to the latest ver 8. i got hit 3 times this month. cleaned and it kept coming back, didnt know why, but i noticed acrobat would start just before hand.
i used malwarebytes andspybot to get rid of it. hope it stays away now.
of course go into safe mode before running scans
fuckers....
pornhub.com is infected by the way