[CentOS] crash after update please help!

For usinging some soft wares in my field of study (biology) I need to
update centos. But there is a big problem.
My laptop is vaio SB31FD.
It is a dual boot system (Centoswith win7). It crashes when I reboot it
after updating the CentOs kernel.
There is not any new line(kernel name) in the grub page. There is  only two
options, CentOs and other(win7)!!!
Win7 is okay, but after choosing Centos the next page is appeared and a
blue line in the button of the page grows from left to right, but when its
colour changes to the gray and one waits to see the login page, it crashes.
There is not any message!!!!
I installed, updated and encountered with this problem 4 times. Now, I am
sure it related to the kernel update.
I tried to solve the problem with "Rescue mode" option from CentOs DVD but
I can not find any helpful command by googling.

also, I did this work on my friend`s laptop(Dell vostro1510), but THere is
the same problem.