I use XP rather than Vista, but you have not had a reply as yet so I will add some comments. What do you actually have open in firefox,

• is it just an image file ?
• if so what sort of file and what file extension is used

or

• is it a a web page that includes .ppg or .jpeg files with in it ?
• if so are you trying to save the whole page or are you right clicking an individual image to save it ?

As an example of a webpage with multiple images some of which are .jpg images try this

My firefox v3.6.13 in Windows XP will open and save

• webpages containing jpg content
• jpeg files themselves
• individual jpeg from web pages

Note if you download a complete web page you will, in most cases, in fact download a multitude of files that make up that webpage, and depending on your Vista settings you may not easily see all those individual files.

I think that I have seen it mentioned that this issue was caused by an extension.
If you give the file a proper image file extension like .jpg to make the OS recognize it as an image then you should get a valid image.

See Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

See also:

• http://kb.mozillazine.org/File_types_and_download_actions

I have this problem as well. The problem is not an extension problem with the hosted file that is being downloaded/saved - Firefox is displaying it properly as an image.

Here is how the issue manifests: I will have an image being displayed in the browser, then right-click on it and select "save image as" and I get the save window. Under "file types" it will say "pdf" - this is NOT a pdf image, it is a straight jpeg image (I am looking at it in the browser, no pdf plugin is used, it's just an image).

If I don't do anything, when it gets saved it is saved with a .htm extension instead of a .jpg extension (not even a .pdf extension - so Firefox seems to be really confused). I did not know this at first because Windows default in Vista and 7 hides the file extensions. Then if I select "save" to save it, and then try and view the saved image with an image viewer I will just see text/garbage. It doesn't happen with all images, just some.

I have had to go the into file/folder properties control panel and unclick "hide extensions." That allowed me to see what extension Firefox was adding, and I saw that sometimes it adds the .htm extension instead of a .jpg, so I have to manually change it to .jpg before it is saved so that it saves properly as a jpeg file instead of an html file. This does fix the problem and then saved images are properly viewable as image files.

It really is very annoying to have to watch that, and then manually change it when Firefox is confused, though.

It does NOT happen on my Mac, by the way, only on Windows Vista and Windows 7 (haven't tried it on XP).

I also have this problem. I am using Kubuntu with Firefox 3.6.22. I can rename the xxxx.htm files to xxxx.jpg and the OS can then read most of the pictures. Those that do not work, I then try to rename xxxx.png or xxxxx.gif

Then they can be read. It's clearly a problem with Firefox.

You may note the page we are on now when we type messages contains both .png and .gif content, on my system (XP) if I save these images they save with correct file extensions, Firefox is NOT saving them as .htm.