Of course, this is not an Installer error. Rather the opposite: the installer FIRST check if the DLL.XML is not corrupted and THEN it applies any modifications. So, your DLL.XML was already corrupted before running the Zurich installer, the installer also told you the wrong line, and it also told you that it hasn't touched the file.
In your case, the issue is probably caused by the last line, that has a \ sign, that of course is not correct XML, and is probably caused by either another installer, or by having modified the file by hand. The message should go away if you simply remove the last line and save the file.