Additional error messages that may be connected to this solution include the following:
A malware or exploit that is removing the Base Filtering Engine service is executing a Windows command (sc delete bfe) which causes the Base Filtering Engine to disappear after a restart. This does not appear to be an issue isolated to Win32/Sirefef but to multiple Rogue Antivirus applications. This is similar to when a Rogue Antivirus executes the attrib command to hide all files.
We recommend that you run the ESET uninstaller utility in Safe Mode with Networking to remove any remnants of previously installed ESET programs or partial installations that might have failed before attempting to install your new ESET product. After removing any previous installations, attempt to install your new ESET product again.
For the successful installation of ESET products, it is important that no other antivirus products are installed on your computer. Typical uninstallation* using the Windows removal tool (Add/Remove Programs) is often insufficient. See our list of Uninstallers (removal tools) for common Windows antivirus software for assistance removing previously installed software. If you do not know whether there is an antivirus product installed on your system, we recommend that you use the ESET A/V Removal tool to scan your system for these types of programs
If your issue is not resolved, continue to section III below.
The ESET SirefefCleaner tool can restore the Base Filtering Engine when run using the /r switch. Follow the steps below even if you do not suspect that your system is infected: