Microsoft Security Essentials won't start. MSE will still perform scans but no matter what I do it won't start
I assume that you mean it will not perform Scheduled Scans, but it will perform Manual Scans.
Windows Vista or Windows 7
1.Click Start, and in the Search programs and files text box, type Appwiz.cpl, and then press ENTER.
2.Right-click Microsoft Security Essentials, and then click Uninstall.
3.Restart the computer, and the go to the "Reinstall Microsoft Security Essentials" section.
If you were able to uninstall Microsoft Security Essentials by using the previous steps, you are finished.
Reinstall : Reinstall Microsoft Security Essentials
1.Visit the following Microsoft website:
3.Click Run, and then follow the on-screen prompts until the installation is complete.
4.Restart the computer.
Visit This site if you want more details -
Thank You -
EDITED to correct link -
Edited by noknojon, 01 July 2013 - 06:27 PM.