HP DV2000 Disabled-

Greetings from aus!, Yesterday my dad brought round his HP pavillion DV2000 running windows xp Professional, now usually I can fix most problems he has but this one is just beyond me, upon turning the thing on I'm greeted with a message:

"Windows could not start because the following file is missing or corrupt: <Windows root>\system32\ntoskrnl.exe

Please re-install a copy of the above file."

Now, I have no idea how to get past this, I tried loading an ISO of XP pro through CD and DVD, but the computer doesn't want to boot up from a CD or DVD drive, I changed the boot order and put the dvd drive up top and that hasn't worked, the message still sits there.

I also partitioned a little bit of my external HDD and turned it into a USB version of the above ^ and the same error has occured.

Please help, I have no idea what this crap is ;D