Hi P3_700,
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:
https://downloadcenter.intel.com/Detail_Desc.aspx?agr=Y&DwnldID=19792
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.