MacBook - keyboard and trackpad not recognized

My trackpad and keyboard both arrent't recognized by my white macbook.
a few weeks ago they just stopt working.
Now I installed the OS X again fresh, but still they don't work.
the on and off button of the keyboard does work.
I tried using an external keyboard, to do the apple hardware check. but that doesn't work. because the external keyboard is recognized to late in de boot, and the hardware check menu won't come.
Is there some kind op app. that cant check my hardware? because I don't think it's the software because I just instaled the OS X fresh.
or do you think it's something else?

tnx,

jorrit