Base Filtering Engine Service (BFE) is a service that controls the operation of the Windows Filtering Platform. Windows Filtering Platform (WFP) is a network traffic processing platform that allows software to “hook” into Windows networking stack. DU Meter depends on BFE for network traffic accounting, and will display an error if BFE is not working properly.
There are viruses/trojans in active circulation that disable and remove the BFE service as a first step in the infection process. Some popular antiviruses can stop the infection, but cannot prevent or revert the deletion of BFE service.
There is no Microsoft-approved way to re-install this service. You can use System Restore to roll back to a previous state when this service was still working. If you cannot do that, and do not wish to reinstall Windows or restore from backup, please read our blog post for an alternative, albeit rather risky, solution.