It suddenly crashed and show the message "Windows XP could not start because the following file is missing or corrupt: \WINDOWS\SYSTEM32\CONFIG\SYSTEM" upon switch on.
Then I tried use Norton Go back to 'return' to 3-day-ago but still the same.
Then I tried using the VAIO recovery disc but it cannot detect I have 2 partitioned discs C&D and said I can reinstall the XP but will erase all data on C. I quit.
Then I insert the XP CD#1, boot using it, and see it asked me to type "r" for activating Restore Console (or Enter to go to the XP install mode).
After pressing "r", it shows a command prompt C:. I know a bit about command prompt and I noticed that when I typed dir/w, it showed nothing.
So I tried chkdsk /r and then the checking start with the % counting.
At 31%, it stopped and said something like disc damaged and cannot proceed etc.
Then I search internet again (until I can get another laptop) and found the Microsoft website or others. They said under the C:>/ prompt after the XP CD with restore console, I can type line by line to mkdir a temp folder and copy some system files from windows directory. That's when I confirm that I cannot mkdir. And with further try like cd, dir, md, the PC said "Access denied".
So from now on. Whenever I turn on the PC, it will ask me to backup immediately as there is a likely disc error. Choose F1 to proceed and F2 to setup. F2 will prompt me to the BIOS screen. I see the primary harddisk is there, no primary slave (or "Auto"). I know nothing about these BIOS so I didn't change anything.
Here are about the history.
Thank you very very much.