[Code]
function NextButtonClick(PageId: Integer): Boolean;
var
  ErrCode: integer;
  DeXVersion: string;
begin
  // initialize the Result to True to allow the setup to start
  Result := True;
  // if the version file was successfuly downloaded, then...
  if DownloadFile('http://dex.wotanksmods.com/latestver.txt', DeXVersion) then
  begin
    // blah blah
  end
  else
    MsgBox('It seems you have no Internet connection...', mbInformation, MB_OK);
end;