Redirect / loop problem when switching language

[MLu]

When customers land on my site via a Google Adwords campaign, I have noticed a strange error when they try to change language

 

The landing url is for example:

http://mysite.com/oscommerce/?campaignId=7399849&adGroupId=7569889&adGroupCreativeId=718992983

(displays well)

 

and when they press another language flag, they get this url:

http://mysite.com/oscommerce/index.php?amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;campaignId=7399849&adGroupId=7569889&adGroupCreativeId=718992983&language=at

 

and this error message (my translation into English): "This webpage has a loop by redirect"

 

What could possibly cause this, and what could I do to solve the issue?

 

Thanks