Dell not booting at all!

Hi
My Dell Dimension 9200 will not boot-up, it will not allow to boot even from the Vista CD I have, it is just freezing at the Dell logo on the boot.
It will not allow me to press F2 or any key as this keyboard won’t even initialise.

any advise much appreciated, pc is less than a year old. The last thing that happened was a Microsoft update which automatically re-started the PC.

it has a Dual-core processor

help!