Can't run slui.exe to activate Win7

I found a similar topic (http://www.sevenforums.com/windows-updates-activation/331953-cant-activate-windows-7-slui-exe-access-denied.html), but I tried some suggested solutions without resolved my issue. From a few days, Windows 7 reports that my Windows copy isn't genuine. I tried to access to "change product key" or "slui.exe", but it says "he stopped working", so I can't use a genuine key to...