WordPress pages not loading sometimes but with no errors

Sometimes, but not all the time, all of the wordpress pages associated with my site http://www.phillybroadcaster.com, won’t appear. This includes all admin and public pages – everything. If I keep hitting the refresh button, eventually the page will load; but when it’s not, two things happen:

For the front end, if I’m accessing the site from the public’s perspective, the URL will show up in the address bar, but the tab will display the full URL as well, not my applied title, with nothing on the page. Just a blank white page.

For the back end, if this thing – whatever it is – happens, it will ask me if I want to download the .php file for the post I’m working on, or the .php code for the respetive plugin or widget or page or whatever I’m trying to access. Here’s a screenshot of what I get.

I really need some help because this problem is discouraging visitors to my site, with which is a project I’m upstarting for an investor.

BTW, this problem started happening about 2 months ago, and happen everyday.