Hp compaq embedded security chip causing problems

I have an HP Compaq dc7900 convertible
minitower dc7900eC/8400/16hq/2U/16rk SA.
Original operating system Windows vista.
Currently there is a new hard drive without an
OS. When I switch it on it displays the
message 'activating embedded security chip'
then it reboots itself repeatedly. I have tried
entering BIOS but it reboots before doing so.
I have also tried resetting the BIOS by
removing the battery and draining power but
keyboard wont respond and system hangs
after memory count. The keyboard I have is a
dell product, it has a PS/2 connection. USB
keyboard wont respond even remotely. Please
help I am clueless here.