You need to enter
nosmp and
maxcpus parameter at Grub or Lilo boot prompt. For example if you are using Grub as a boot loader, at Grub prompt press 'e' to edit command before booting.
1) Select second line
2) Again, press 'e' to edit selected command
3) Go to end of line and type two parameters
nosmp maxcpus
4) Press enter twice and b to boot system
5) This will prevent the kernel panic and system hang scenario.
Once your system is up using single CPU then you can run diagnostic commands such as:
Get all boot message:
Find out if problem with PCI cards
Find out what device drivers loaded (if something is missing then your driver will not get loaded)
Get memory info (is memory detected correctly?)
Code:
free
cat /proc/meminfo
Get CPU info (see if your CPU hit by any bug):
Find out your kernel version:
If kernel is old then update it to latest stable release from RHN using
up2date command