I would check the SMART status of the hard drive. If it has bad sectors, it could take a long time to boot into Windows, making you think there's a fault with the screen. An easy program to check the SMART status is Crystal Disk Info. If it's anything other than blue, I consider replacing the drive and installing the OS. If you have a linux boot disk, the disk utility in Ubuntu or Mint will tell you if you have any bad sectors and you'll see if it goes through POST and boots into the OS in a faster manner.