Here's how they are set up, if it helps. We have no wireless connections, just cables-cables-everywhere (I'm waiting for wireless to get to a more stable technology before I switch the house over. Maybe a few years from now). Poopsiedarling is my old computer, not the one I use now, and acts as a "host" to the internet for all the other computers in the house, and has two network cards. One is connected by cable to a multiport hub, and every other computer in this house plugs into that hub. The other network card is connected by a cat cable to the Comcast-provided device (I am not actually clear in my mind if it is a "modem" or a "router"

which has one cable to poopsiedarling, and the other cable plugs into the same cable setup as the TV, I guess (I don't use the TV much).
Since the numbers for poopsiedarling.mshome.net are ok, I'm assuming the problem does not exist between the multiple household computers and the poopsiedarling computer, but instead along the cable coming out of PD's second network card, going into the comcast device (could this device be the "no response from unknown host" listing?) and then into the wall.
So I guess it sounds like a good thing to try next, might be turning off and resetting the comcast box, and maybe also a reboot to ol' poopsie.
If that doesn't work, we have several cables with rather loose connection-clips that yes sometimes jiggle out (especially if the four cats have been exploring the area). So I might order some replacement cables with new and better connector-clip-thingees, that snap in more snugly.
It sure seems like if there was 100% packet loss (and it says that every time I check), that I would have constant unplayable connection. But I usually don't, just sporadic intervals when I get kicked off with the mangled network data message. When I try the online Bandwidth Speed Test at
http://www.bandwidthplace.com/speedtest/ , it shows my connection as 3.3 megabits per second. And it doesn't seem to affect family members who are playing world of warcraft etc. (Also, problems don't seem to be any different at 4 AM when I am the only one on, vs 4 PM when a housefull of kids are logged in).
Anyway, thank you. I'll see if resetting that device does any good, and cross my fingers.