Followup:
After being told on the sixth tech supervisor visit that there was some indication of "packet loss" from one of my pieces of equipment I asked whether the modem could be the culprit. (All other hardware had been changed and the odds of two consecutive defects in either the host or client unit are pretty long). The tech indicated that a malfunctioning modem could be a problem despite the filter they routinely place on the modem line to screen out interference with the DVD system. So I replaced the modem myself, re-booted both the host and client box and have had a week of perfect functioning from the system! So - fingers crossed - it appears the problem is resolved. Hope this may be of help to someone else.
gr1940 - I agree with your comment but it's wasted on domino. Despite his erudite pretensions, it's clear he doesn't understand the meaning of the word "help" in the context of the Cox guidelines.