Error 1601: "Windows Installer is not accessible"
Try the following solutions, in the order listed, until the error goes away.
- Restart your computer, and then try installing or updating again.
- Change the Windows Installer properties:
- On the Windows taskbar, click Start, then choose Control Panel.
- Double-click Administrative Tools, and then Services.
- Locate and open the Windows Installer service.
- Verify that the startup type is manual and the service status is stopped. Then try installing or updating.
- Download the Windows Installer, and then try installing/updating again.
- Finally, if the error persists despite following the solutions above, follow the steps at the Microsoft site.