I updated my machine to Windows Installer 3.0 and then upon reboot I would get Error 997 when trying to start the Windows Installer service. The message associated with the error has to do with "overlapped I/O", so I mistakenly thought that maybe something was still trying to be copied or got corrupted while being copied during the Windows Installer installation. Re-ran the MSI for Windows Installer 3.0, rebooted, but still got the error.

Resolution is to unregister and re-register MSIEXEC.EXE. Another classic example of the text of the error message having fuck-all to do with the actual problem.


    msiexec.exe /unregister

    msiexec.exe /regserver

It's also recommended that the SYSTEM account have "Full Control" permissions to the HKEY_CLASSES_ROOT hive in the registry.