Disable and Stop the Themes service.

With the default Category Control Panel:

Head to Start
Select Control Panel
Select Performance and Maintenance
Select Administrator Tools
Select Services
Select "Themes" service (Double Click)
Select General Tab
In the Startup type: select "Disabled"
Select the Ok button to close the panel

With the Classic Control Panel:

Head to Start
Select Control Panel
Select Administrator Tools
Select Services
Select "Themes" service (Double Click)
Select General Tab
In the Startup type: select "Disabled"
Select the Ok button to close the panel