Since some time back, I simply couldn’t save images in Firefox. When I right-clicked on an image and chose save, it won’t give any errors but it wouldn’t save the image. However, note that dragging the image onto the desktop would save the image on the desktop.
I finally found the solution on this forum: http://www.velocityreviews.com/forums/t368807-p2-cant-save-images-in-firefox.html
In simple terms, you just have to delete the file download.rdf from the path: C:\Documents and Settings\[your user name]\Application Data\Mozilla\Firefox\Profiles\vlcl3pr1.default\
Don’t worry it won’t crash your application and you won’t lose any data, at least nothing like that happened on my PC.