Exchange 2007 services won’t start after Windows Update
HOWTO: Resolve Windows Update Issue
This particular problem is caused by installing KB2756918 on a Server 2003 x64 machine running Exchange 2007. I don’t know the specifics, I just know how to fix it.
Windows Update Solution:
First you have to rename two “machine.config” files located in C:\windows\microsoft.net\framework64\v2.0xxx\config and C:\windows\microsoft.net\framework\v2.0xxx\config Rename machine.config to machine.config.old and copy machine.config.default in the same directory and rename the default config file to “machine.config”. Make sure to do this in both directories.
Reboot the server and your Exchange transport service should be able to start.
If your OWA doesn’t come back up and you get a message “service unavailable” even after a few iisreset commands you may have to re-register .net v2.0 with IIS. To do this enter the aspnet_regiis.exe command with the –I flag. Here’s an example for my directory structure.
After that, restart IIS and check to see if your OWA is working. Send a couple test messages and make sure to hide KB2756918 from being installed on the server to avoid this issue in the future.
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