A growing problem with new computers is that if you need to reinstall the OS, the damn thing won't
reliably boot from DVD or USB memory. The major problem here is that when it fails to boot off the selected media.. it then boots from the hard disk. Why, oh why, are the
damn things designed like this?
If an unintended HD boot happens when you're trying to wipe a possibly infected HD, then that means any media connected to the computer has to be regarded as suspect. I can't count the number of workshop DVD+Rs I've thrown away or USB keys I've had to format after this happening. Plus, there's the constant risk of overlooking one which did an uncommanded HD boot, and having our systems infected as a result.
Somebody needs to get the designers of these systems sat down in front of a copy of 'Malware For Dummies' and make the read the thing from cover to cover. Then, give them a mighty kick in the pants.
I keep an old Maxdata computer for wiping HDs precisely because it will boot reliably from DVD, and not 'fall through' to booting off the HD if the DVD fails to read or is a bit slow starting. Unfortunately to cap it all you now are faced with tablets where taking the HD out is a major pain, so that route is not always available.