OWA e2k3 "Error: Access is Denied" on a newly build cluster

Strange one this (as my posts tend to be)! Two nodes of a cluster, both newly build. Both W2k3 SP2 and E2k3 SP2.

Clients were getting "Error: Access is Denied" in the browser. We tried this locally and we saw that thsi was happening on the back end directly as well.

We followed the article on this to find out whether permissions on exchweb etc were correct. They were.

It was then found that the w3core.dll file had not updated correctly along with other IIS files with the applicaiton of SP2.

Checking the version number of the two files on the respective nodes showed this conclusively.