Hi, this is my first time using this site, so if I'm missing some vital piece of information, such as a log, I'll post it as soon as I have it once you tell me. A couple days ago I noticed that my microsoft security essentials was not running, and when I tried to start it up, it gave me an error. I downloaded MSE from the website and uninstalled/reinstalled it. after doing so, I updated virus definitions and ran a quick scan, which found the sirefef trojans (sirefef.y and .m), and when I tried to remove them sirefef.y says it was not found (the details say it is in C:\Windows\System32\services.exe->731) and I received a critical shut down error which promptly restarted my machine in 1 minute. Every time thereafter I tried to log in it gave the same critical shut down error, and I was completely unable to rid myself of the issue. After trying to go into safe mode I got the same error (I assume because it is a part of the services.exe file), so was unable to do anything. I am able to use my computer right now because I did a system restore to an earlier point where the new version of security essentials was not yet installed. Because the version of MSE I had was non-functional I have deleted it from my machine entirely at this point, and I ran windows defender offline to try and clean my machine last night. it had the same issue that MSE had the first time, in that it was unable to get rid of sirefef.y in services.exe. I have searched online with a different computer for information, and I found the only reliable method that was described was a manual cleaning, and because of the sheer volume of registry and other pieces I would have to get rid of through that, I am terrified of doing so. I would definitely appreciate any help that you could give. I am running windows 7 64 bit professional - service pack 1. Edit: because I am currently not getting the critical shut down error and because installing and running MSE was what caused that in the first place I am not confident about installing any antivirus at the moment.