On some web pages (not even all pages for the same site), trying to view the page (either by typing in the URL or clicking through a link to it) causes Firefox to download the page to a HTML file on my desktop rather than display it directly. The downloaded file appears to be correct HTML (I can open it as a file in Firefox and read it). The file is apparently downloaded as "Web page, HTML only" rather than a "Web page, complete" since included graphics do not display. For example, http://www.bottlebiology.org/basics/index.html displays this problem but http://www.bottlebiology.org/intro/index.html does not.