Error i SharePoint Sandboxed Code service

I have pressed in Visual Studio 2010
Visual C# -> SharePoint -> 2010 -> Empty SharePoint Project
and then
Start debugging (F5)
 
But I get this error:

Error 1 Error occurred in deployment step 'Activate Features': Timeout occurred while running the SharePoint Sandboxed Code service. This service is required to run sandboxed solutions in SharePoint. Please ensure the service is configured correctly in SharePoint.
0 0 SharePointProject1

 
What does it mean? How can I fix it?