My Laptop is running Vista HP 32 and Microsoft security essentials (MSE). I have been running MSE since its intro without any problem. I recenty noticed that Windows defender did not work any more. So I decided to remove and reinstall MSE. This processes worked OK. Now, the antivirus and firewall work OK, but Windows Defender does not activate. I have not been able to find a solution browsing the web. Can you help?