Ok,it is necessary to you uninstall Combofix.

Start >> Run

Combofix /Uninstall

Enter. Then do the following

Open Notepad and Copy/Paste everything from the Code box into Notepad:


Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run]
"avast5"="\"C:\\Program Files\\Alwil Software\\Avast5\\avastUI.exe\" /nogui"
* Go to[b] File > Save As[/b]
* Save File name as [b]nogui.reg[/b]
* Change Save as Type to [b]All Files[/b] and save the file to your [b]Desktop[/b]
* double-click [b]nogui.reg[/b] on your Desktop
* When it asks if you want to merge the info to the registry, hit YES/OK
  Reboot computer