How to Unregister Windows Installer

1. Click 'Start' and 'Run' to open the Run dialog.
2. Type 'MSIEXEC /UNREGISTER' into the Run dialog and click 'OK.'
3. Click 'Start' and 'Run.'
4. Type 'MSIEXEC /REGSERVER' into the Run dialog and click 'OK.' Windows can't install applications if you skip this step.