User Preference trouble

I tried to open the tab but everytime i click it blender crashes. I was opening it to emulate the numpad and now im going to use luxrender which requires me to open user preferences but everytime i opened it it just show the not responding screen.

Change any window to a User Poperties Window from the dropdown list in the bottom left hand corner.

Thank you to both of you.
I was having the same problem. Now, thanks to you two, I have a workable solution.