The fact that you can't resolve names is the real stumper here. Your inability to ping to the IP address could be related, though.

It really seems like you have *something* blocking access to the internet to PING and Ping Plotter. This is what you've got to get tracked down. Do you use a proxy server? Are you certain that there is no software running on your computer that may block DNS lookups? Have you installed any software to aid DNS name resolution?

What operating system are you running?