Page not found

This is probably stupid but after 2 hours, I’m fed up: I created all the pages in needed, went in menu, created Main Menu, put my pages in it, selected it for use as main navigation. The menu appears OK when visualizing the website, but only the homepage works. All other webpages give a “Page not found” error, event though my permalink pref is set to postname. Example : http://localhost/siatris/services/ (for the Services page) returns a page not found. I also changed my reading settings as per the Help file in the folder of Aqua. I also checked in the database, it does say /%postname%/
What could this be ?