That is caused by the way ComboFix does its job. ComboFix has been known to cause false positives in many AV programs. With that said, please review this topic: ComboFix usage, Questions, Help? - Look here.
ComboFix is a very powerful tool that should only be used with expert assistance. One last thing...
Note if you find ComboFix unavailable: There may be times when the developer will remove ComboFix
in order to update or fix reported bugs so the tool may be unavailable for download.Never attempt to download ComboFix from sites other than BleepingComputer.com and Forospyware.com!
Other sites hosting ComboFix are not authorized mirrors and are hosting outdated copies of ComboFix.
These outdated copies can contain bugs that may render some machines unbootable.
Using unauthorized mirrors of ComboFix puts your computer at risk of not booting again.
Always wait wait for the official version to be fixed and released again.
"In a world where you can be anything, be yourself." ~ unknown
"Fall in love with someone who deserves your heart. Not someone who plays with it. – Will Smith