My HP dv9700 series laptop developed a problem in that it would boot up and then shut itself down.
I managed to access the dos info and it stated "TPM error".
Now this TPM turns out to be the "Trusted Platform Module", a piece of Hewlett Packard software/firmware that does nothing else other than police what software the machine gets to run.
It is of no benefit to the user but in my case has failed and subsequently trashed an otherwise fine PC.
Apparently its a common cause of failure of the Hewlett Packard machines, and HP arnt interested in fixing it.
Neither do they warn people in the sales rooms of this latent defect.
There is a fix I believe which involves replacing a chip at about 300 $.
Whatever you do dont ever buy a HEWLETT PACKARD PC.
They are designed to fail you.