lamave-wp on "[Plugin: Wordpress Flickr Embed] JSON string error"

Hi!
I just installed the flickr embed plug-in and all works fine up til the time I want to upload photos. Whenever I click the flickr button on the visual board, the ffg message appears:

AJAX error: parsererror (SyntaxError: Unable to parse JSON string)

I am also running on a PHP 5.3. How can I make this plug-in work? Thanks!

http://wordpress.org/plugins/wp-flickr-embed/