When trying to install 1.52 I get the following error message:

Download: Setup is now downloading additional files to your computer.
File: updallocator.php (1 of 1)
Status: resolving www.safer-networking.org

When this times out I get a popup that says:

Error sending request.
The server name or address can not be resolved.

I was able to install 1.4 and when it completed it tried to update to 1.52 and I got the same error messages. How do I fix this?