I have a ze4560us laptop that cannot find the OS at boot-up. I tried loading the disk from the DVD drive but it loads all the executive files up to the NTFS file system and stops. It does not report an error, it just hangs at loading NTFS. I replaced the HDD and same result. The BIOS incorrectly identifies the new HDD but it does see it. I did increase from a 40GB drive to a 320GB drive, but no difference. Any ideas?