Each of these Apple discussions is a couple of pages long, but have you tried these:
A possible solution in one was, I just managed to fix the problem! I went into the Preferences (hold down Apple icon top left of screen and select "System Preferences"), clicked on the "Time Machine" icon (next to last row towards the right), and slid the ON/OFF switch to the OFF position. Like magic...no annoying error message! All I have to do now is remember to turn it back on now and then to back up my laptop.
Each of these Apple discussions is a couple of pages long, but have you tried these:
A possible solution in one was, I just managed to fix the problem! I went into the Preferences (hold down Apple icon top left of screen and select "System Preferences"), clicked on the "Time Machine" icon (next to last row towards the right), and slid the ON/OFF switch to the OFF position. Like magic...no annoying error message! All I have to do now is remember to turn it back on now and then to back up my laptop.
From the second link you posted: "I had the same problem. We definitely traced it to Time Machine. The "Fix" was this: plugged in and designated different external HD as Backup volume. Then plugged in the original disc (after testing in in a different machine) and now the computer recognized it and error message stopped popping up. The Apple tech was as puzzled as I as to why this worked, but perhaps, forcing the machine to re-recognize it (or maybe even, gettting it recognized by a different machine first) somehow worked some magic. (Since posting this in another chat, several people have been successful. Good Luck!)"
This is the only permanent fix at the time that i have found.