I downloaded your plugin recently and it has stopped working for some reason. It may have been due to an SSL install & ip address change but I'm not sure.
Warning: file_get_contents() [function.file-get-contents]: Filename cannot be empty in /XXXXX/XXXXX/public_html/site/wp-content/plugins/facebook-fan-box-cache/facebook-fan-box-cache.php on line 287
I can see it attempt to create an image in the cache (0 bytes) then fail. The temp html is downloaded there and at a glance appears ok.