okay, so today i turned on my imac, the 2005 white version, and was downloading a chinese movie. the movie finished downloading, i opened it to check it was working with some subtitles i had downloaded. somewhere during this time i was also updating or doing something with norton antivirus, and it gives me a message that the vulnerability protection is corrupted or something like that. i ignore this for the time being. then i went to work on a powerpoint. halfway, i needed some pictures so i opened iphoto, but iphoto wouldnt open. iphoto had the question mark in the dock, which means that finder cant find it. as a result, i immediately went to the applications folder and saw each of my applications being deleted. i have no idea how this happened, but i immediately shut down my mac to prevent other files from being deleted. could this be a potential mac virus, and how do i deal with it?