Safari Cant Find Server

This is what happens; i type in a URL of my favourite website. Then this thing comes out saying Safari Cant Find Server. I know that the URL isnt wrong and that the website exists. So does anyone know how to solve this?

Need lots more info in order to help you troubleshoot, such as:

Mac Model? OS X version? Version of Safari? What happens if you try a different browser? Does email and other non-browser Internet stuff work correctly?

etc etc.

this computer:
MacBook Pro OS X version 10.8.5
Safari:
Version 6.0.5
What happens:
I can't even install because it doesnt take me to the website, it just says 'safari... blah blah'.
Email is going OK.

Since you are communicating with us on this website, you must be using a browser. Which one is it?

If it's Safari, are you meaning to say that SOME websites (like this one) load fine, but others do not?

yup, Im using safari, and SOME websites work.
like this one

Can you give us one that doesn't?

Do you have any plug-in's installed in Safari .
If yes, can you disable all of them and try again. If that works, enable the plug in's one by one.
Secondly, Do you have the " Develop " Menu available in the menu bar ?
( You can activate that in Safari/Preferences/Advanced )
You can instruct Safari to pretend it is another version / even another browser.
Maybe that is the culprit.

Cheers ... McBie