pages not loading until I click a second time - please help

Hello have been using my new mac since april - and its been great! I am using safari, but today whenever I try and load a web page you know the little bar that zaps along well it just stops somewhere between a quarter and a half way - I then just double click or re-fresh the bar and the page loads fine - I have

a) Reset by hub,

b) Shut down Mac

c) I have tried Chrome, but this is now the same

Please help, as far as I am aware I have not made any changes but this is driving me up the wall -

please help x