When someone click on the navigation under program some

Hi,
When someone click on the navigation under program some links does not work the first time , when you click it bring an unknow page and if you click a second time then the real page appear. (it only happen the first time you connecting to the page i believe, i had various customers reporting this problem)
http://www.salon-du-bien-etre.org
I have granted you access, would appreciate if you can let me know what is wrong
thks in advance
Jacques