Brian Posey wrote an article that is worth taking note of. He explains how to recreate the IIS virtual directories for OWA. This can be useful if there is corruption in the metabase, or if data deletion occurs to the files and folders needed.
Link to the article:
http://searchexchange.techtarget.com/general/0,295582,sid43_gci1167561,00.html?track=NL-368&ad=541160
Overview of steps:
1. Backup IIS - This will ensure that further damage isn't done
2. Delete all the IIS virtual directories
a. Exadmin, Exchange, ExchWeb, Microsoft-Server-ActiveSync, OMA, and Public directories.
3. Delete the DS2MB metadata using Metabase Exploerer (IIS Resource Kit)
a. DS2MB stands for Directory Service to Metabase. It exists to bring over configuration information from AD to IIS. Remember that some OWA administration is actually done through ESM. Those changes come over with the help of DS2MB. I'm assuming that when DS2MB is deleted, the virtual directories are repopulated using the information in AD.
4. Restart the System Attendant and/or reboot the server to recreate the virtual directories.
5. Reset permissions on the ExchWeb virtual directory.
a. The article recommends enabling anonymous access and integrated Windows authentication on the ExchWeb directory. Anonymous access was already enabled when I tried this in my lab, and Integrated Windows Authentication was not needed.
KB Articles:
Overview of DS2MB
How to reset default virtual directories that are required to Provide Outlook Web Access, Exchange ActiveSync, and OMA
