Problem with bilingual web site opening the front page in the second language when set up as default

Hi,
I have bilingual web site (using version 2.0.3.2) and when the second language is set up as default the front page always opens in English. I've tried resolving this by clearing the cache , but the result was the same. I will appreciate if someone can help me resolve this problem.
Thanks,

Try to clean your cookies and your browser's cache. Cookies also count.

Done that too, the problem still remains,
it seems that Open Cart automatically detects the language in the browser and gives priority over the language settings in OpenCart
Any ideas how to fix this?

I did some further investigation and we tested the web site in 4 different browsers:
1. Safari - opens correctly in the second language (set as a default language)
2. Firefox - opens in EN language
3. Chrome - opens in EN language
4. Internet Explorer - opens correctly in the second language (set as a default language)
It looks that the language detection method used was not properly configured in: /catalog/controller/startup/startup.php
Could someone more experienced in coding suggest a modification in the code in the startup file ( /catalog/controller/startup/startup.php) , so the language setting in Open Cart takes higher priority in detection of the language?
Thanks,