OWA Fix
Run Script Fix
At flashing cursor, type the following commands

If you are using Exchange 2010

1. CD “C:\Program Files\Microsoft\Exchange Server\V14\Bin” and then press <ENTER>
2. Subdirectory will change to the above.
3. updatecas.ps1, then press <ENTER>

If you are using Exchange 2007

1. CD “C:\Program Files\Microsoft\Exchange Server\Bin” and then press <ENTER>
2. Subdirectory will change to the above
3. UpdateOwa.ps1, and then press <ENTER>

The script will perform a number of different commands, and then simply complete by dropping you back to the DOS prompt
Type EXIT to close the Shell window