I am getting a problem that is rendering the system completely unreliable:

The problem is showing in two different computers:

Computer 1:
Hardware: Atlon 32bits 3000+ with 1G RAM memory
Red Hat Advanced Server 3 + Oracle 10gR1

Computer 2: Atlon 64bits 3500+ with
Hardware: Atlon 64bits 3500+ with 1G RAM memory
Fedora Core 4 + Oracle 10gR2

The computers freezes completely, there is no video, no keyboard or mouse reaction. They answer to "ping", and nothing more works.

Sometimes we see the CPU usage going to 100%. That should not be the case as the computer 2 is trully fast.

The computers freeze only if you have the oracle running.
If you do not start oracle, the computers run ok for weeks.

I apreciate if you can give at least a hint of where to find solutions or log files that could help trace this problem

Thanks in advance