LaTeX.org

Texmaker works without any trouble on macosx 10.9 Maverick

With the -insert foo option to the command line, a latex command (foo) can be inserted by an external program to the current document while Texmaker is running.

You tried to save a file without extension. Just add the .tex extension.

I'm on Windows 7 and I've tested. There is no trouble. Syntax highlighting works fine after saving a document.