A: 

This probleme disappeared as it came when I displaced all my HTML code in a file that is called by

browser.setUrl("http://my.url-string.html");

So In fact I can't solve the problem but It does not bother me anymore...

ps : the method to get my local page Url (that I have put in the same directory as my java file) is Class.getRessource("My File Path to which I can add its path in the classpath")

Ar3s