Working on my friend's laptop, pavilion dv4, it's having start-up issues. The laptop powers on and won't load the OS (vista). It shows the message 'Err1Err3' and nothing happens from there. I tried running diagnostics with the vista recovery disk but after loading the cd, i only got the windows loading bar and than a blank black screen that never changes. Can't run any tests. Could this be a motherboard problem? HDD? Any help would be greatly appreciated.