So, here's what worked for me; I hope it will work for you!:
In Windows Media Center (WMC) go to:
Settings | TV | TV Signal | Set Up TV Signal | @ the warning you'll need to click "Yes"
... from there I just followed the prompts.
After "Set Up TV Signal" runs, which can take some time, you'll need to go to:
Settings | TV | Guide | Edit Channels (&, I would assume, "Edit Favorite Lineups" if you use 'em) & you'll have to RE-deselect all the **** channels you don't want, & RE-"Rename" channels, etc.
You'll also want to go to your "Series" & double-check 'em... there was one Series I had long-long-ago Canceled that was magically back, a couple others that were doubled
(I canceled whichever twin didn't show any upcoming programs to be recorded), & at least one Series
(that I've noticed so far) that had completely disappeared, no longer scheduled to be recorded at all.
However!: Although after RE-running "Set Up TV Signal" the WMC Guide
did actually Update
(for ~2 weeks as it used to), still, for a while WMC kept sending the, 'You've only got 3 days of listings!, you need to update the Guide!' scare-messages; I don't know
if it was the standard WMC 'Client Maintenance' (mine runs @ 6am) or rebooting
(after an unrelated Windows Update), but for whatever reason, eventually it stopped doing that, & everything WMC-Guide-Update
seems to be back working correctly how it used to
(knock on wood!).
After all that happened, responses started getting posted saying Microsoft Windows Media Center had switched from Zap2It to Rovi,
(thanx So-CalMountainMan, etal), & sure enough, now when I go to: Settings | TV | Guide | About Guide Listings, where they used to be from Zap2It, they're now from Rovi.
So, WHY didn't Microsoft deal with this Zap2It
-to- Rovi transfer in a caring & respectful manner toward its millions of Windows Media Center users!;
WHY is up to us to figure out what would be such a simple matter for 'em
...if they gave a damn ...maybe 'cuz Microsoft is ditching WMC in Windows 10?, so to hell with all us WMC users...
... thanx very much all who responded!
w