Problems with booting

Hi,

I've just installed Centos 5.3 x86_64 into a CPU. I've done a yum update to update the version to Centos 5.4. I then installed mysql, php, apache and phpmyadmin into the system.

After the installation of phpmyadmin the screen suddenly goes blank, but the monitor is still on, and the cpu is also still on.

I offed the CPU and oned it back again. This time, the screen shows the booting of Centos then goes off.

Why is it like that and how do I resolve it? Is it a video card problem?

Thanks.