If you are trying to run ComboFix on your own due to malware infection, please be aware that using ComboFix is only one part of the disinfection process.
As Broni advises, no one should be using ComboFix
unless specifically instructed to do so by a Malware Removal Expert. Please read the pinned topic ComboFix usage, Questions, Help? - Look here
After posting your logs in the proper forum and your Helper instructs you to run ComboFix then you will need to follow those directions. ComboFix will not run until AVG is uninstalled as a protective measure against the anti-virus. This is because AVG "falsely
" detects ComboFix (or its embedded files) as a threat and may remove them resulting in the tool not working correctly which in turn can cause "unpredictable results"
. Since AVG cannot be effectively disabled before running ComboFix, the author recommends you to uninstall AVG first.