Error 1500 - Another installation is in progress.

Problem

When trying to install, a "Error 1500. Another installation is in progress.  You must complete that installation before continuing this one." error message.

Solution

A previous uninstall was not fully finished, and some uninstall processes are still pending.  This issue is system dependent.

• Cancel the current installation.
• Open Windows Task Manager - Details tab.
• Locate the msiexec.exe processes
• Select each msiexec.exe and click on End Task.
• Repeat this operation until all msiexec.exe are closed.
  Windows will then reboot and let you install.