Service pack won't install
I'm trying to put Vista service pack 2 on a Pavillion dv9500 laptop, but it continually fails. It apears to install fine but as soon as it reads step 3 of 3 100% it will say, could not install, reverting back to older version.
I've tired running it in safe mode with all services and startup items disabled (except the services windows needs to run). Also tried removing the second HDD but it still won't take.
Any ideas, or should I just reinstall windows?