When you go to the google.com website, Google automatically directs you to it’s country specific web search for the country it thinks you are in.

For example if you’re in Australia, google.com will automatically redirect you to google.com.au. For Singapore it will be google.com.sg

These country specific sites will be displayed in the language for that country and provide search results which is most relevant for that country.

However if you are using a proxy which is located in a different country, you might be redirected to a country specific google site which is not that country which you reside.
This is especially true if you work for an international company which have their proxy servers in a different country.

To work around this, go to http://google.com/ncr.
This is an alternative web address for Google.com that always takes you to Google.com without redirecting you.
It’ll set a cookie to force your search results to go back to using plain old google.com (make sure you have cookies enabled!).