@elainebosse
There should be no need to tweak your .htaccess. However, I am a bit puzzled. When I go to your site, I get an IIS 404 error page. If your site is on an IIS server, then I believe that there is no such file...
I know that some people had problem with IIS servers (I can't make tests). I made some changes to help but it seems that it does not solve every cases. There is a proposed solution at the end of this topic: http://wordpress.org/support/topic/home-page-shows-posts-in-both-languages-iis?replies=15
In my case, works with this option "http://sample.com/language/en/", but this is not nice
That's why Polylang defaults to the other option but keeps this one. Just in case... It seems to help some people even if I don't know why.
@cguillou more informations and a link would help
To all, *always* test Polylang with a default theme and without any other plugins to check for a conflict. Some plugins and themes don't follow the right way to flush rewrite rules and break WordPress as soon as they are used together with a plugin which defines its own rewrite rules.
http://wordpress.org/support/topic/the-translated-pages-doenst-exist?replies=19
http://wordpress.org/support/topic/404-everywhere-3?replies=9