I have upgraded the kernel 2.6.9-55.0.12.ELsmp to 2.6.9-78.ELsmp.
After upgrading i got the following Error in message logs.Then i rebooted the server.now it is working. But i want to know why was the kernel panic and can it happen again;
kernel: kernel BUG at kernel/exit.c:904!
kernel: invalid operand: 0000 [#1]