Permalinks with .html

Hi

Having a very frustrating time getting permalinks to work and would appreciate any help. I have a three page site, Home, Works, Profile. Home is a static front page, Works is the posts page and Profile is a page.

I am trying to get my site working with /%postname%.html style permalinks but most of the time only /%postname% ever seems to work. If I type in the url with .html I get a 404 error. When I do manage to get /%postname%.html working all of my pages show the posts page except for my front page. I can’t see how the two scenarios are connected but the setup of the permalinks ether does one or the other. Has anyone come accross this?

a+
gar