It is possible that you accidentally clicked the 'Block Images' item in the right click context menu while trying to save an image. Check the image exceptions: Tools > Options > Content: Load Images: Exceptions - See Settings for web content, pop-ups, fonts, and languages

A way to see which images are blocked is to click the favicon (Site Identification icon) on the left side of the location bar and click the "More Information" button. This will open the Security tab of the Page Info window (also accessible via Tools > Page Info). Go to the Media tab of that Page Info window. Select the first image and scroll down though the list with the Down arrow. If an image in the list is grayed and there is a check-mark in the box Block Images from... then remove that mark to unblock the images from that domain.

See also Fix problems that cause images to not show and http://kb.mozillazine.org/Images_or_animations_do_not_load

The above suggestion didn't fix the problem I'm having. I see see all images if I use IE but not in Firefox. I don't want to have to use a different web browser. But I do use FB all the time and therefore I want/need to see those profile pix.

Did you check in Tools > Page Info > Media if there were any image that have a check mark in the "Block Images from..." box just above the Preview area?

If the images are not blocked in Firefox then maybe an extension or your security software is blocking the images and you need to look there.

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

No help there as none of the block images boxes are checked. I've looked in my security program and there is nothing there that would cause this. I appreciate all your help. Pat

Tadaa! I found the problem based on a link you posted above. Thanks so much! Pat

You're welcome Pat.

Can you tell us what fixed your problem as that can help others with a similar issue?