Blank images from media in Safari

I’m using the plugin “Thumbnail for Excerpts” to grab a thumb from a post (uploaded via the post’s media uploader) and display it in the excerpt on the main page. Looks/works fine in Firefox, but in Safari it shows a blank image below each one.

http://www.marcosjsaldivar.com/portfolio/

Can anyone point me in the right direction for resolving/working around this? I know I could probably do a work-around by not using the media uploader, but that seems like a fairly poor solution. Thanks!