When "Save Link As..." is used, file permissions are changed so that other users of the same computer have full access.
I have a laptop running Windows Vista Ultimate, and I'm not sure what's been changed in my Firefox, but now, every time I use "Save Link As...", the user permissions for the file have been set to include "USERS" which is then indicated by an icon in the bottom left corner of the file thumbnail. The icon is of the two people you see under "User Accounts and Family Safety" in the Control Panel.
I do remember a dialogue box coming up saying something about "This file originates from another computer and may be harmful..." or something along those lines when this problem first occurred.
I thought that problem would only occur for files from one website, but now, whenever I try using "Save Link As...", the user permissions for that file are incorrect.
If I open the link and download the file manually, it's perfectly fine.