After every scan with COMODO Cleaning Essentials a number of “Rootkit.HiddenFiles” were found in the folder ‘\RSA\MachineKeys’. They were removed but after every start-up they were back again.
I went to the forum ‘HijackThis’ and followed several instructions, several days after each other.
In the end the conclusion was, that these must be files that Microsoft make themselves so that it has to be a “False Positive” of COMODO Cleaning Essentials.