Microsoft security essentials freezes up I have use it before successfully but not now I have tried 3 or 4 timew with the same non result

Microsoft security essentials now stop when it feels like it freezes up sooner of later the last time it was running for 20 hours ... then froze up ... 20 hours seems ridiculous ..

Can someone help me with this I am an old guy ( as in I was 20 when television was invented) computer problems are for young people to solve ... But I can trim a hoof and shoe a horse...