It could just be registry entry remnants. How did you remove MSE, you said deleted, which should be uninstalled, is that what you meant ?

Have you any entries in the task manager for Microsoft Security Essentials (I haven’t a clue what they would be called, never used it).

You can also check the services and see if there is a service running, press the Windows Button + the R key and type services.msc and click the OK button.

If you find anything in either task manager or services.msc for Microsoft Security Essentials then end the task or stop the service.