Hi! This morning when I turned on my computer, the Microsoft Security Essentials won't start nor update, so I uninstalled it and used CCleaner to delete registers from my computer. Next I reinstalled the MSE, made the updates and during the first scan the antivirus does after it is installed, it detected two trojans (Sirefef.Y and Sirefef.B) but before the antivirus get to make the appropriate actions, there was a window saying that Windows has encountered a critical problem and it would automatically reboot in a minute and MSE couldn't remove the trojans. After that, every time the PC starts, this window appears telling that Windows will reboot and I can not do anything to stop it: ( My operating system is Windows 7 Professional (x64) and I'm from Brazil. From what I've been seeing here, this has been a popular problem this week but the solution (more specifically the FRST script) is specific to each particular machine, so I anticipatet the first step and did the scan with the FRST on the USB flash drive and took the log that the program generated Thanks in advance!