I found one on your /page/4 - the Wordless Wednesday image IMG_6902.JPG
putting just the image path into the browser (...timthumb.php?src=//wp-content/uploads/2010/0...) shows me two // in front of wp-content, should be one. Insert the path in customfield without /.
Additionally it shows the error:
Fatal error: Allowed memory size of 31457280 bytes exhausted (tried to allocate 13056 bytes) in /home/ckac........
This means you are getting memory problems on your server, which could solve from alone but actually happens because the image is quite big: 3.202,92 KB 3.264px × 2.448px
On this single post you display this 3MB image just 493px wide, but force visitors to load the full big image.
My advice: Resize your images to a width of about 600px before uploading, you never need wider images to display, you save server space, traffic volume and timthumb saves memory.
Did this help? You are welcome to ask.