Was just wondering if there are any known issues with a thumbnail being generated is the image in the post is a .bmp?
The thumbnail is either being shown in Firefox as a broken image (on a windows box running Vista) or the Alt tag (on a linux box and on a mac). The display of the Alt tag is a bit of a problem as it is rolling out over the link text.
http://wordpress.org/extend/plugins/wordpress-popular-posts/
