Just because you can not see anything else being "installed" does not mean you should interrupt the installation process.
This message is coming up only when I try to install certain things like updates, so as I result i cannot install those updates. Even if i turn off the computer and then after restarting try to install the updates it still comes up with the same message. I can then try to install another type of programme and there is no problem, it just says code 1500 etc on certain programmes.
1 - Navigate to "Services and Applications" in Computer Management.
Right click on Computer then click Manage.
NOTE: Do this under login with Administrator rights.
2 - Expand the Services and Applications
3 - Click on Services
4 - In the right side of window, sort by Name.
Go down to Windows Installer.
By default the start up type will be set to Manual.
You will notice that the status will read 'Started' even though you know that it is not really running.
5 - Right click on it and select properties.
6 - In the middle of the popup box, you will see Startup Type.
Use the drop down arrow and select 'Disabled' and click apply.
7 - Close all windows and reboot.
The service is now set to disabled so on reboot it will not still think it has been started.
Follow the above steps again and select 'Manual'.
Click apply and close all windows.
Now you should be able to run the installation of whatever software you were attempting to run when you were receiving the error.