Pinterest badge links your blog to your pinterest profile by showing your recent pins. Also shows the follower count and follow button as well.
This is a problem with your PHP setup. You are almost certainly running PHP4. The plugin requires PHP5. WordPress requires PHP5 after version 3.2 too. Talk to your host about using PHP5.
You probably have something other than your Pinterest id in the id box. Make sure you just put in the correct pinterest profile id and nothing else.
This is a HTTP 403 error from Pinterest, it means they have banned your server’s IP from making requests to their servers. This usually isn’t anything to do with the plugin (it makes very few calls to Pinterest's servers) and it is more likely that you are on shared hosting, and someone else who shares your IP has been scraping Pinterest.
The plugin requires either CURL or file_get_contents() to be enabled on your server.If your host gives you access to your php.ini then you can change the ‘allow_url_fopen’ setting to ’1′ which will fix your problem. Otherwise speak to your host and ask them to enable CURL or allow_url_fopen for you.