I also run Windows XP and I often run into this problem. In my experience, there are several things that can produce that error message. The first thing to do is right click on the file, click on properties, and make sure that the "read only" box is not checked. If it is checked, uncheck it, hit "apply", and get out of the dialog box. Repeat this procedure to make sure that the "read only" box really is unchecked. Hope this works! Please mark the problem as solved if this works, or if you no longer have the problem. Otherwise, please get back to this thread and post what happened when you tried my suggestion, or post more information about your problem in case my suggestion was "off the mark". (If I understand your problem correctly, it is not related to firefox, but rather to the settings on the file that you downloaded.)