I have problem for my computer when i replaced a new HHD. At the beginning, it was working when it started to install the system. For some reason, i stopped the process and cloesed the power. Then i restarted it again. When i started it again and booted up from CD-ROM. It doesn't work any more. It always says that invalid system disc. I don't know what i did cause this problem. Please give me help.