Sorry for the late response. You have 2 options:
1. It may be that your hardware is new and isn't supported by RHEL 4 or
2. you may have a hardware issue (problem)
RHEL 4 has some nice updates if u have a valid subscription. The last update for RHEL 4 is Update6. Try to get it from www.redhat.com
. And try to install it on your new configuration.
If it is indeed a hardware problem then you must check for your components. I suggest to check first for your memory then go for hdd and if the problem is bigger go check your motherboard, cpu, graphics card. For memory try testing it with Memtest86+. And for the hdd go to your manufacturer company (e.g. if it's Seagate which is in your case go to seagate website and download the tool for verifying your hdd integrity).
As for parthasarathy problem as I already said try updating for the latest version of RHEL which is Update6. If u have RHEL 4 and Update1 or below it will not detect your hdd.