Just check and make sure you marked the new drive as "c:/ drive in the bios settings, Maybe this could cause a prob. I replaced a HDD in my Dell and forgot to make sure it was marked for :C drive, when I loaded the O.S. it tried to send to :C which was now my floppy HAHA! after i changed the configuration everything was fine, Also is your power supply rated for your new hardware?? Just some thoghts.