Using IE or Firefox, I get the same error message:

Unable to connect

Can't establish a connection to the server at www.google.com.

 The site could be temporarily unavailable or too busy. Try again in a few
   moments.
 If you are unable to load any pages, check your computer's network
   connection.
 If your computer or network is protected by a firewall or proxy, make sure
   that Firefox is permitted to access the Web.

I have tried all the suggestions listed, and still no success.

HELP!

Try clearing cache and cookies If you don't know how to clear cache: How to clear the Firefox cache If you don't know how to clear cookies: Clear cookies and site data in Firefox

I was unable to connect to any Google site or use any search utility for 3 weeks. I finally contacted McAfee technical support and after giving them full access to my computer they solved the problem in less than one hour. I had to give them full access to my computer.

The first problem they encountered was the inability to remove some of the virus protection software. They installed a special program which did the trick.

They rebooted the computer several times. I can't describe exactly what they did although I was watching the screen.

I am very pleased with the result. My suggestion for anyone else who encounters this particular problem is to purchase and install McAfee virus protection on your computer and then take advantage of the free technical support. I paid $39 for the program but received over $100 in support.

Chatting with a computer nerd is much easier than taking your computer in to a shop. It is also cheaper.

Just to let you know, if you have McAfee then you have to configure it to work with firefox. We have steps on our site to help you with that, Update McAfee Security Center and firewall settings to allow Firefox access to the Internet

In your case，this issue is resolved.

This is a good idea and was done but it did not solve the problem.

I am unable to use most of the google websites that I use at work on Firefox, but I am able to use them at home on Firefox. I cannot open igoogle, gmail or my calendar, very frustrating!!!

Can't establish a connection to the server at www.google.com.

The site could be temporarily unavailable or too busy. Try again in a few
  moments.
If you are unable to load any pages, check your computer's network
  connection.
If your computer or network is protected by a firewall or proxy, make sure
  that Firefox is permitted to access the Web.

I've tried deleting cookies and using safe mode etc etc, but nothing helps. Is there something I'm missing. It worked for a week or so on this computer, but just suddenly stopped, my mother has the same problem - HELP PLEASE!

I contacted tech support at McAfee and during the chat gave them total control of my computer. It took them a while. They had to employ some additional programs that were not available to me. They could use to remove programs and malware from my computer. Then they reinstalled McAfee.

I think I mentioned that McAfee and three other programs were unable to locate any problems.

Somewhere along the line they corrected the problem. I can now access Google and any other search engine.

McAfee tech support did what the computer repair shops told me would cost $100 to $150. I paid less than $39 for the McAfee software and computer support for a year.