IIS 7.5 URL Rewrite stopped working after reboot

Question

The server has 2 IP addresses. Each is bound to a site. One of them has a bunch of url rewrites configured for each application, pointing to another server. Each have anonymous authentication enabled.

After a reboot of the server, the url rewrites stopped working, simply showing an "Unauthorized" error page.

Info:
Window Server 2008 R2  Enterprise SP1
IIS 7.5 SP1

Answer 1

I noticed that the error page said that no authentication was enabled except integrated authentication. The GUI said something different though.

I switched on Basic Authentication (additional to Anonymous) and it worked immediately. When I switched it back off, things continued to work again just as they did before the reboot.

This seems to be some glitch in IIS (?)