Microsoft released an Windows Installer Service update on August 12, 2014, KB2918614:
This update has seemingly affected installers for many different applications, including Elgato Game Capture HD.
To resolve the issue, please uninstall the KB2918614 update.
1) Open the Control Panel
2) Select "Programs and Features"
3) Click on "View Installed Updates"
4) Look for "Security Update for Microsoft Windows (KB2918614)", and highlight it.
5) Click on "Uninstall"
6) Reboot your computer
7) Install Elgato Game Capture HD software again