Microsoft Security Essentials (MSE) is one of the excellent freeware antivirus from Microsoft and it runs on Windows without much memory footprint. If you are running MSE on your computer and it crashed due to any changes you made to registry, then Fix MSE should be able to help you.

Fix MSE utility will restore all registry values & service settings to known good defaults, without re-installing MSE. This utility works fine on both 32 bit and 64 bit Windows. It supports Windows XP, Windows Vista and Windows 7 operating systems. Note that you need to have installed Microsoft .Net Framework 2.0 and Microsoft Security Essentials 1.0 to run this utility.

All you need to do is to download and extract the file to see Fix MSE folder, double click on Fix MSE.exe file and click on Fix MSE button to fix the errors.

Download Fix MSE Utility