I was given an installation disc for windows 7 by my sister. I tried to use the disc, however this message 'cannot use on this unit. Attempting to load a 64 bit application, however thus CPU is not comparable with 64 bit mode' appeared. Although I am not entirely sure, I believe my computer is a 32-bit. I have a Hp compaq d530 cmt. My computer will no longer start up. Is there any way to fix this problem?