Replacing your systems hosts file with a custom file is an easy way to block dangerous sites from communicating with your computer. The idea is that when your computer is asked to goto a link, it has to check for the address of the site. Before asking the public internet for the address, the system is configured to attempt to look up the address in the hosts file. By following the instructions on the site below, you can replace your standard hosts file with a file that will intercept any requests for known bad sites and send the traffic back to your own computer generating an error.
Give it a shot.