If by "factory settings" you mean an unhacked exe then you weren't very clear in your previous post.

If so then other things to try are disabling AV software to see if that allows it to work. Beyond that the only other possibility I can see is Vista's virtualisation routines being behind it. Have you tried installing 6.31 into another location without a pre-existing mirc.ini so that it saves it's settings to your usefolder?

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