It looks like there's a problem between your computer and hop 1 (Comcast). This could be a problem inside your own network, or with your cable connection.
If you have multiple computers on your network, you might try pinging another computer inside your network and see if you get similar results. If you get no packet loss on that, during a period where you're getting packet loss when pinging externally (using a second instance of PingPlotter), then you should get in touch with Comcast to have them troubleshoot. If you get packet loss when pinging the other comptuer on your own network, then it's more likely a problem on your own network.
