Can anyone help me with the following?, now and again for some reason,when I download a photo from one of my facebook albums, it goes to my documents in a preview image obviously, but when I try to view it full sized,it remains at the preview size...but not every picture does this....

Just surmising, but it might well be the original photo wasn't very big in the first place.

To save pics from facebook are you clicking download or right clicking then 'save as' / 'save image' ??