How do I manually uninstall SQL Express if uninstalling from Add/Remove Programs fails?

The officially recommended uninstall order for these products can be found at this location. However, this order is not enforced via the Add/Remove Programs control panel and it is pretty easy to overlook the readme and uninstall in alphabetical order or some other random order and get into this state.

If you encounter either or both of the above error dialogs, you can use the following steps to resolve the errors:

1. Download and run msiinv.exe using the instructions in this previous blog post
2. Look at the output from msiinv.exe in a text editor such as notepad and locate each of the products that are installed that have SQL 2005 in the name
3. Click on the Start menu, choose Run and type cmd
4. For each of the SQL 2005 product codes found in the msiinv.exe output, run msiexec /x {Product Code} from the cmd prompt - this command will likely generate the same errors shown above but it is good to run it just in case
5. Download the smartmsizap tool
6. For each of the SQL 2005 product codes found in the msiinv.exe output, run smartmsizap.exe /p {Product Code} from the cmd prompt

After running smartmsizap to cleanup each of the SQL 2005 products left behind on your machine, you should be able to successfully install later builds of SQL Express and/or VS 2005.