bonekrusher is correct, IE will only complain if the file is not well-formed, i.e. it's not XML, when attributes aren't quoted or an unescaped ampersand is present for instance. The way around this is to check before hand if it is badly formed by loading it into a parser first and then either save it with a txt extension before opening in IE or to open it in something like Notepad.
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Joe (
Microsoft MVP - XML)