|It is probably your CPU that is overheating. Check your CPU fan is still working as that is the most likely culprit.|
There is nothing I know of that will shut down a hard disk if it overheats. They just don't get hot enough to warrant it.
A CPU, especially an AMD, will fry itself withing seconds without adequate cooling so some kind of shut down mechanism is essential. A P4 has internal mechanisms to shut it down. AMD rely on external systems to shut it down.