The problem has been resolved and a new, thoroughly tested within the security community, version of ComboFix has been uploaded to Bleeping Computer. However, the reminder continues:
ComboFix should not be run unless specifically asked by a trained malware analyst. It is not an ad hoc scanner or an antivirus tool. Due to the power of this tool, it is strongly advised that you do not attempt to act upon any of the information displayed by ComboFix without supervision from someone who has been properly trained. Doing so may lead to problems with the normal functionality of your computer.
It is additionally advised that ComboFix should only be downloaded from the authorized hosting location at Bleeping Computer.