Firefox continually says it "cannot find the server, try again" when I attempt to open it. What could be wrong?

When I click on any of the Firefox links on my desktop, a page usually opens saying that Firefox can't find the server. It then gives me the option in the form of a button in the lower left corner of the box, to try again. Sometimes clicking the button works and I am connected to the server, but often I have to close the page, wait a few minutes or even restart my computer, in order to connect to the server. It's extremely annoying.