I update my version of WP to the latest release.
Everything was ok (made some minor fixes to my theme). But then I wanted to login as admin. ik give my credentials. And i got redirect to a page like:

http://www.fototim.be/zenphoto/C:\domains\fototim.be\wwwroot\zenphoto\zp-core\admin.php

I use IIS.

Thanks in advance.

Fixed it.

I replaced auth_zp with an older version.
Problem was an incorrect path in the cookie + an incorrect redirect path.

What version?