I am sorry you are having this problem with the system but let me help you out.
I regret to say that the Intel® Processor Diagnostic Tool works for newer processors only. You can check at following link (end of page) the processor that supports the application:
The Pentium III is an Legacy product by now and the Pentium processor mention on the Intel® Processor Diagnostic Tool are the newer with Intel® Core architecture.
It would be nice if they didn't Re-Purpose old Names. For me a Pentium came after the 486 and before the P2. Why Not call it something new or original like. "Pentium Dual Core". Perhaps Ford will introduce next years model, the "Model-T"