Pagination and URL Rewrite

Hi everybody.

I’ve got a problem on the pagination of my blog :

My initial configuration :
Permalink settings : – Postname : /%postname%/
Reading Settings : static page : Post Page – Blog
=> I can’t reach the page 2 of my blog

The only configuration “working” :
Permalink settings : – Default : ?p=123
Reading Settings : static page : Post Page – Select (none)
=> I can go on page 2 through /?page_id=23&paged=2

FYI :
Blog is a page
I use Posts with additionnal field added by Magic Fields 2.

I really don’t want to use the Permalink Default setting but I don’t really understand what’s going on.

Does someone has an idea of what is going on ?