OS: Windows XP SP2
At first, I entered into BIOS to disable the integrated display card by option 'AGP'->'PCI', then rebooted computer till windows flag flashing appeared, following,the whole screen was blank and nothing was not seen.
I think maybe original display card driver is still in OS that cause the phenomenon and the new display card did not drive correctly. I tried to repair Windows SP with CD and the isse was solved at last. However, the issue appeared again when turned off power and rebooted it. Why? Any help are appreciated.