Quayzar

I recently purchased a Dell Inspiron 6400 with windows vista already
installed. ever since the very first time i tried to turn it on the power
button refuses to work correctly. when the computer is turned off completely
and i attempt to turn it on by pressing the power button, the computer does
nothing. no lights turn on, the screen does nothing. however, if i then
press the Dell MediaDirect button on my notebook, the computer will turn on
and go directly to the MedaDirect UI. since this does not actually boot
windows, i then click on exit which turns off the computer. if i press the
power button shortly after that the computer will finally turn on the boot
windows.

How in the world is this happening? can anyone help? thanks