My linux could not get reboot after un-properly shut down. It gave me message "segmentation fault" then hung there. Now I try to back up the data in the hard drive, say A, by reading it from another linus computer, say B. I set this A drive to be a slave (cable selection, the second connection of secondary drive), but it always go to boot from A, not from the B (primary drive). Any suggestion for the set up? Also I tried to use installation disk to get into rescue mode, then I found the network connection was not set up, althrough I did click set up network connection when reboot it. When I tried to ifdown eth0 or ifup eth0, I got segmentation fault again. Is it possible to recover the data back from the hard disk when segmentation fault message keeps coming up?

Thanks a lot...

Did you have the network card working before you got the segmenation fault?
If not try a different network card if it did run memtest86. (which should be one of your kernel options on the live/install cd)

Memtest site:
http://www.memtest86.com/

Info on Segmentation Faults.
http://cs-www.bu.edu/help/unix/segmentation_fault.html