Answer: This is boot related problem. There will be same questions repeated two times but problem is different.
First When you restart the system you will get the Error:
File Not Found
mount: error 15 mounting ext3
mount: error 2 mounting none
switchroot: mount failed: 22
umount /initrd/dev/: 2
Kernel Panic: no syncing: Attempted to kill init !
This error occurred in your system before showing welcome redhat linux. That means problem in grub boot loader.
Restart the System
Check the grub boot loader configuration by pressing e shortcut key.
You will see like:
root (hd0,0)
kernel /vmlinuz-2.6.9-5.EL ro root= / rhgb quiet
initrd /initrd-2.6.9-5.EL.img
OR
root (hd0,0)
kernel /vmlinuz-2.6.9-5.EL ro root=LABEL=/root rhgb quiet
initrd /initrd-2.6.9-5.EL.img
Then Edit Boot loader to make like
root (hd0,0)
kernel /vmlinuz-2.6.9-5.EL ro root=LABEL=/ rhgb quiet
initrd /initrd-2.6.9-5.EL.img
Check all lines and edit as same as above. Press b to boot the system
After booting the system you should correct the /etc/grub.conf file.
If still you are getting Error likeFile not found, it seems that either kernel file or initrd file is missing. To troubleshoot with these problem, boot the system on rescue mode.
linux rescue
chroot /mnt/sysimage
Check the files on /boot, if not available install the kernel package from ftp or nfs server
Create the initrd image file on boot using: mkinitrd initrd-2.6.9-5.EL.img `uname –r`