Error Downloading Exchange Address Book

I seem to be having the same issue i had a few months back where the OAB stops downloading, However if i add the authenticated users to the OAB virtual directory in IIS they can then download the OAB again, however these rights keep on disapearing every week. I raised this on http://social.microsoft.com/Forums/en-US/partnermsgexchange/thread/7c44b1d7-7969-4a76-b0a3-ce1e0bc5894b

So if the offline address book stops downloading to clients please complete the following as a temporary fix:

Go to all 3 of the CAS servers: exchangecas1.domain.com / exchangecas2.domain.com / exchangecas3.domain.com

Goto Internet Information Services (IIS) Manager / expand port.entagroup.com / Sites / Default Web Site /

Right click on OAB and go to Edit Permissions and add authenticated users with Just read right. (you may also need to do this with the actual OAB directory under the OAB directory)

For more info go to the Gold partner forums:
http://social.microsoft.com/Forums/en-US/partnermsgexchange/thread/c7da9e42-0725-47ec-98c2-8ea4acfab77f
http://social.microsoft.com/Forums/en-US/partnermsgexchange/thread/7c44b1d7-7969-4a76-b0a3-ce1e0bc5894b