Can't open anything I download!
Just yesterday, after absolutely no problems, I downloaded a file and it said i couldn't open it because I didn't have permission. It said to click the "get info" button and change permissions. My user already had full permission. I dismissed it and deleted the file; it was downloaded from the internet, after all. However, now any time I try to open any file I've previously or recently downloaded to the internet, I can't. I can't even open any screenshots I've took.Please help, this computer is not even one month old, I can't afford to have any problems!!
MacBook Pro, Mac OS X (10.7.4)