So at this point I dont think it is the machine its-self as it has been completely reformatted with a new OS?.
We replaced the hard drive in that machine and installed a fresh copy of Win 10, and a new licensed copy of office 2016 pro plus thinking that Win 8 may be the culprit. Initially the problem was occuring on Win 8.1 Office 2016.
etc etc, but they are only temporary fixes and the problem returns anywhere within a few minuites to several days.