Some websites not working ?

[Mr Advice]

Well as it is a network issue, only the server can fix it, it is not client side fault. Try googling your error and see if there are any forums that have a solution. I don't think it's client side fault, otherwise no websites would work for you.
I'm no expert, but I have some suggestions:

If you use a modem, or whatever device you use to connect to the internet, remove it for a while and then add it again. Check your IP configuration, you see the windows logo button next to Ctrl? Press it along with r, and a run dialog box will appear, in the box type cmd. (Which is Command Prompt)
If the windows logo and r don't work then locate it from the start menu > accessories and it will be in the list.
When you open CMD a black console window will appear, type ipconfig, this displays your
Windows IPconfiguration, or type netstat -a, this shows you all the networks you are connected to. On the right, most should say LISTENING.

Sorry I can't help further. If your firewall is working correctly then it is definately a network issue and should be automatically fixed soon. If it was your firewall that was the issue then your browser wouldn't be able to access any webpages. Think you are just gonna have to wait.