Hi all again,
Guess what... I have the solutiooooooooooon !! Yes i'm happy.
More seriously, i followed all your pieces of advices before creating another Web Application (delete IE cache etc.).
That was finally the best thing to do. I decided to create it the same way i created it for the first Web Application, and i still don't see where i did something different than this time.
Whatever, after creating this new Web Application and a Site Collection, with only the Administrator account authorised on it, i tested the permissions by creating a group with a new account and a Read permission, and by deleting the access for this last user to a specific library. And it worked. BUT, i couldn't see the difference between the two sites in all of the People and Groups parts (Site permissions, Groups)...
So the error couldn't be at the Site Collection level, i started to search differencies at the Web Application level.
I found the problem in the Central Administration > Application Management > Policy for Web Application page.
Indeed, i had 2 lines in my first Web Application :
(All zones) -- NT AUTHORITY/Authenticated_users -- NT AUTHORITY/Authenticated_users -- Full Read
(All zones) -- Search Crawling Account -- NT AUTHORITY/LOCAL SERVICE -- Full Read
Whereas in the second one i had only one line :
(All zones) -- NT AUTHORITY/LOCAL SERVICE -- NT AUTHORITY/LOCAL SERVICE -- Full Read
I thus suppressed the first line to create a user identical to the new Web Application, and everything works now.
Actually, I don't understand the grounds of the problem :
- Why these configurations where different because i don't remember having changed them => Is there a possible link between the People and Groups page (where I hadded authenticated_users) and this Web Application page ?
- Why is there a Search Crawling Account in the first Web Application ?
- Foremost, what is LOCAL SERVICE ?
I hope my questions are not too stupid, and that you didn't waste your time helping me.
Whatever, i thank you a lot because without you, i wouldn't have found the issue.
Thank you again,
Gzave.