Blank White page w/o the (www.)

I get a white screen when I put in website.com but the site comes up when I put http://www.website.com adding the (www.).

How can I fix it so that the site comes up with and with out the (www.)?

Also I noticed that on my other sites with similar installs, when I type website.com.. they convert to http://www.example.com, and load the site correctly where as my problem site does not. It stays blank, and does not “add” the www prefix.