VLC - Set as default for MP4 on Windows 7

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I'm having no success in trying to set VLC Media Player (v2.07) as the default player for MP4 files. I am using the control panel applet, Default Programs, and I have tried the both appropriate options there (default programs; set associations).

Is this "by design" in Windows 7? Can I get around it?

[edit]
I should have said that I want this for when logged on as Standard User. If I log on as Admin, the cp app does work - ie, the changes "stick".