I downloaded and installed steam and was happily play tf2. the next day i went back on and steam just wouldn't open. I decided to delete steam and the .dmg and redownload and reinstall it. however, i couldnt because it said that 'The operation can’t be completed because the item “Steam” is in use. (same with the dmg.) the application was obviously not in use. I decided to reopen the dmg, and put the steam application in the applications folder but steam still wouldnt open open and cant be deleted. I now have two versions of steam and the dmg that cant be deleted becausethey the mac thinks the're in use when they are not. HELP!!!