Problems with installing WSS SP2

Some months ago a customer wanted to install all missing patches on two of our Sharepoint environments. One of the missing patches was Windows Sharepoint Services Service Pack 2 (WSS SP2). Unfortunately the admin that was installing the patches wasn't aware that the SP shouldn't have been installed. During the installation of the SP something went wrong, I am not exactly sure what, causing WSS to be uninstalled instead of upgraded. This resulted in a broken Sharepoint Portal Server 2003 installation. The Sharepoint Portal Administration service wouldn't start anymore, the Central Admin virtual server was gone, the ISAPI filter in IIS was gone and the files in the "C:\Program Files\Common Files\Microsoft Shared\web server extensions" folder were also gone.

The only error messages I got were:
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* System log:
Source: Service Control Manager
Event ID: 7000
Description: The SharePoint Portal Administration service failed to start due to the following error:
The service did not respond to the start or control request in a timely fashion.
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* Application log:
Source: .NET Runtime
Event ID: 0
Description: The description for Event ID ( 0 ) in Source ( .NET Runtime ) cannot be found. The local computer may not have the necessary registry information or message DLL files to display messages from a remote computer. You may be able to use the /AUXSOURCE= flag to retrieve this description; see Help and Support for details. The following information is part of the event: .NET Runtime version 1.1.4322.2300- spsadmin.exe - Common Language Runtime Debugging Services: Application has generated an exception that could not be handled.

Process id=0x4d0 (1232), Thread id=0x1684 (5764).
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The strange thing is that the eventlog indicated that the SP had been installed correctly: "Installation Successful: Windows successfully installed the following update: Windows SharePoint Services Service Pack 2 (KB887624)"

I have no clue if this might have been of any influence on the problem, but the problems occured when WSS SP2 was installed using Microsoft Update on a small (1 server) and a medium farm (2 servers). A large farm (3 servers) on which the WSS SP2 was installed at the same time in the same way was upgraded correctly.

The only solution to repair the environments was:

• Manually uninstall Sharepoint Portal Server (repair and uninstall failed with an error message)
• Remove the C:\Program Files\Sharepoint Portal Server folder
• Remove the SPSAdmin, SPSAlert and MSSharepointPSSearch services (e.g. via XNet - www.kixtart.org)
• Remove the HKLM\Software\Microsoft\Sharepoint Portal Server registry key
• Remove the HKLM\Software\Microsoft\Sharepoint Portal Server registry key
• Remove the Microsoft Office Sharepoint Portal Server 2003 item from Add/Remove Programs via the registry
• Reinstall SPS2003
• Do NOT use the old config database, but create a new one
• Restore the portals by using the existing databases
• Restore team site virtual servers by extending new ones (create new database), add the old database and then remove the newly created database
• Reinstall all webparts, styles, themes, etc

After performing these steps, one of our environments refused to index the portal and WSS sites. After consulting and troubleshooting with Microsoft, I ended up with reinstalling the entire environment.

I hope you won't encounter the same problems as I have, but in case you do, the above instructions will work to restore your environment. It has taken me about three days to fix something somebody else broke in 30 minutes.