I open a case with CA about this and we solved it. Here're he things we do:
1. Give "read&execute" and "read" permissions on all folders and files on the service desk installation path to the IIS_IUSRS.
2. Go to IIS Manager > server > sites > Default Web Site > caisd
3. Go to Authentication on the right side.
4. Disable Anonymous Authentication and Enable Windows Authentication.
5. Restart IIS.
6. Go to Application Pools (On the left pane, below the server name).
7. On the left look for DefaultAppPool, right click on it and select Advanced Settings.
8. Look "Generate Process Model Event Log Entry".
9. Select "Identity".
10. Click the '...' button.
11. On the dropdown select "LocalSystem" then press Ok, ok again.
12. Restart the IIS.