function Enable-MSIInstallation {

    pushd
    
    cd hklm:\Software\Policies\Microsoft\Windows\
    if ((test-path -path Installer) -eq $false) { md Installer | out-null }
    cd Installer

    if ((Get-ItemProperty .).DisableMSI -ne $null) { Set-ItemProperty . -name "DisableMSI" -value 0 | out-null }
    else { New-ItemProperty . -name "DisableMSI" -value 0 -PropertyType DWORD | out-null }
    
    popd
}

function Disable-MSIInstallation {
  
    pushd
    
    cd hklm:\Software\Policies\Microsoft\Windows\
    if ((test-path -path Installer) -eq $false) { return }
    cd Installer

    if ((Get-ItemProperty .).DisableMSI -ne $null) { 
        Remove-ItemProperty . -name "DisableMSI"
    }
    
    popd
}