To uninstall any MSI installation that fails to uninstall itself for whatever reason, use the MSI Cleanup Utility:

http://download.microsoft.com/download/e/9/d/e9d80355-7ab4-45b8-80e8-983a48d5e1bd/msicuu2.exe

This version of Windows Installer CleanUp Utility works correctly in all 32-bit and 64-bit versions of Microsoft Windows.

MSI cleanup utility

The following will show how to clean up Ultidev Cassini when the standalone Cassini uninstaller fails.

1. Download the file to the root for example c:/ and execute the msi installation from there. Note: It is important that you run as Administrator.
2. Open Services.msc and find the service Ultidev Cassini. Right click on the service and click properties.
3. Click on the recovery tab and change the First Failure to Take No Action.
4. Stop the Ultidev Cassini service.
5. Click on Start, All Programs and select Windows Install Clean Up and run the Windows Install Clean Up Utility.
6. Select UltiDev Cassini Web Server for ASP.NET 2.0 and click on the Remove button.

This will remove all registry settings related to the installation, and then you can go ahead and delete files of the failed installation, which in the case of Cassini are

• “C:\Program Files\UltiDev\Cassini Web Server for ASP.NET 2.0” and
• “C:\Program Files\UltiDev\Cassini Web Server Explorer” folders.