Because you logged them as HTML files, you can't open it in Notepad (well in fact you can but I think it is too much pain to pick the original messages from all complex HTML tags.) absorbation suggested you to convert your HTML log files to plain text files. Give it a try!
Also if you really hate Log Viewer that much, you can change the default program which will be run when you click "Open chat log" from inside Messenger through Messenger Plus! Live's
Registry Settings. When the page opens, read the text in the first paragraphs and then search page for
ChatLogOpenWithViewer, and apply those settings to your registry. Good luck!
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