I'm afraid you shouldn't keep it this way.
By commenting the line, the resident protection for DOS programs was completely disabled.
Start regedit, please, and navigate to the key
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\VirtualDeviceDrivers
What is the value of VDD?
Value of VDD:
gpib-vdd.dll
C:\Arquivos de programas\Alwil Software\Avast4\aswMonVd.dll
C:\Arquivos de programas\Alwil Software\Avast4\aswMonVd.dll
C:\Arquivos de programas\Alwil Software\Avast4\aswMonVd.dll
C:\Arquivos de programas\Alwil Software\Avast4\aswMonVd.dll
C:\Arquivos de programas\Alwil Software\Avast4\aswMonVd.dll
C:\Arquivos de programas\Alwil Software\Avast4\aswMonVd.dll