I'm in the habit of deleting everything that goes into my downloads folder within my user folder because having a bunch of installers sitting there is pointless.
Recently, however, whenever I attempt to delete any of these installers within my downloads folder, it tells me that "I need to permission to perform this action." These files can't be in use by anything and as administrator I don't see why it suddenly will not allow me to delete this things after I've been doing it for months.
If I restart the computer, it WILL let me delete these things. But never before that.
your computer might be using these downloads, try task manager to check. It sometimes happens to me if I leave the program I download from open, i.e Limewire, must be closed before you can delete files.