OWA owaauth.dll "440 Login timeout" W3SVC-WP event 2268

Something strange happened. After i applied the rollup 4 on another server the owa stopped working. First symptom was that if you tried to log in you've redirected to the login page without error. Second symptom was that event 2268 from w3svc-wp was logged.
In case of a broken logon.aspx i backuped up the auth directory. I took a look at the settings of the virtual host and changed the path of the ISAPI filter to the old one. Now the error was gone but still couldn't log in cause of the wrong path. At that point i got a little confused and tried to reinstall the rollup and recreating the owa direcoty without success.
After some research and thinking if found a few people who said that the passwords of the IUser and the IWAM user could get messed up or another security problem. Resetting the passwords didn't work but then i got the simple solution:
Edit the ntfs rights of the auth folder and give the authenticated user full access.

Another boring problem that wasted my weekend.