I saw that someone was having a problem very similar to mine here, but like him, I wanted to be safe by creating a thread unique to my situation and specifications. Like him, it appears I have a rootkit virus that has become part of the operating system. Every time I boot the computer up and log on, within a minute, I get an error message that says It then restarts the computer, thus restarting the process all over again. No matter what user I am logged onto, the problem is the same. Therefor, my supsispicion is to say that it is a rootkit virus. Now, before resorting to post my query here, I had attempted to solve the problem myself to no avail. This virus had only popped up and reared its nasty head recently, in fact, as I was downloading Microsoft Security Essentials. So either it could have remained latent until the new antivirus software was installed, or possibly it hitched a ride with the software itself. Whatever the case, the problem still remains. I had looked up possible methods to root out the virus (of course, on another computer) and tried to empliment those methods, but obviously they didn't work (or else I wouldn't need to be here). Here are the nuts and bolts: Software: Windows 7 (32-bit) RegClean Pro Microsoft Security Essentials McAfee Antivirus (license expired)Hardware: Desktop Gateway 506 GR Pentium 4 ProcessorMethods Used in Removal Effort:Search in RegEditSearch Computer for sirefef fileRan Yorkyt --> Got Yorkyt.exeThat should be enough to go off of. Any help and guidance on the removal of this virus would be appreciated. Thank you.