CentOS 5: Grub problem after installing

A black screen with a blinking cursor. It was working previously with Fedora 9. Late found that the boot order was changed in the BIOS, the hd1 was in front was hd0, but hd1 does not have a boot sector. It works after I changed boot order to boot from hd0 first. But I do not understand how the boot order was altered during the installation.