Is Microsoft Security Essentials any good?

I can't remember the detection rate but I have read good reviews about it and so I gave it a try. I was very disappointed with it. I once scanned my school teacher's pen drive and MSE detected and deleted a few viruses which were worms. Knowing that worms can replicate itself within the short time span between detection and deletion. I rescan the pen drive. I observed the scanning progress. Right before my very eyes I saw MSE missed the very same virus (worm) and came out with a clean report. Giving MSE the benefit of doubt and also thinking, may be I wasn't looking carefully, I opened the pen drive. In an instant, there occurred something like a flash on the desktop and my file options were gone and the task manager disabled. I quickly turn off my computer and restarted it in safe mode. When safe mode came on, I made a system restore without running any other program. After that I removed MSE and reinstalled Avast Home Edition. Avast has never failed me like this. I have tried Norton but it seems to be only good at detecting 'spyware' cookies.