Ya know what pic...I have Microangelo and never noticed any change, but in trying animated gifs without it, it appears that the last IE update (probably January's) changed it. You can change the ext before downloading it in the name file box by adding the ext you want, but it mis-configures the pixel size and changes the frame rate to 1. If you try it in another browser (or you don't have the updates installed), it works.
MS finally addresses it by taking the option away...grrrr