After the instal the Red Hat 7.3. The PC restart and It shows me the following message: GRUB Version 0.91 (63k lower / 326644k Upper Memory) [Minimal BASH-like line editing is supported. For the first word, TAB lists possible command completions. Anywhere else TAB lists the possible completions of a device/filename.] grub> I don't know how to solve this problem. Can somebody gives help on this. Thanks

Basically it means that your grub has not been setup correctly and if you are a newbie, put your redhat cd in the cd drive and boot into it. At the first boot prompt type rescue and then follow the instructions on screen to reinstall your grub bootloader. Do you know what partition you installed linux on? If you know that: grub> root(hd0,x) hit enter grub> setup(hd0) hit enter grub> quit hit enter and reboot.

Looks to me like your boot loader got screwed. I suggest you pop in your Red Hat 7.3 installation cd and reinstall the boot loader using the Upgrade/Update option. On the Red Hat 8.0 cd you need to update at least one app (even if you already have it installed) or else it won't update the boot loader. Have fun :-)