>iTunes 10.0.4, or did you mean 11.0.4?
Uh, yeah...😊...I'll edit that to fix it, if I can.
GOOD NEWS!!! I got my problem fixed.
The first tip off that it wasn't Apple's servers was that I got Match to work on my MBA. I did this by clearing the Safari caches, opening iTunes, turning off iTunes Match, turning it back on, "Add Computer."
Then I had to tackle my MBP. I'd had problems with it all morning. Truth me told, I had been retoring the files "iTunes Library.itl" and "iTunes Library.xml" from TimeMachine backups—over and over—in an effort to retrieve a Playlist I accidentally deleted last night.
So I learned the hard way that when you restore those two files (alone) it can muck things up.
The fix:
In Safari, use the Develop menu (you can look through this thread or search to find out how to display the menu) to Empty Caches. Then, on the Safari menu, Reset Safari, and have the following four boxes checked:
Remove all website data
Remove saved names and passwords
Remove other AutoFill form text
Close all Safari windows
Next, in the iTunes folder, delete ALL files but LEAVE the folders. I ended up deleting (on purpose):
iTunes Library Extras.itdb
iTunes Library Genius.itdb
iTunes Library.itl
iTunes Library.xml (I didn't have this one on the particular TM backup I used, but it's often there)
Next, use TimeMachine to restore those files that were deleted from yesterday afternoon's good copy
Now, open iTunes. Turn Match off. Close iTunes. Reopen iTunes. Turn Match back on.
This time, finally, for the first time to, iTunes Match blew right through the first phase of Step 1, and then continued on, finishing matching 15,000 songs in less than 5 mins.
I actually have 15,949 songs. The first time (shown above) I ran the fix, I very briefly saw a popup screen flash that began "Due to the number of songs in your library..." blah blah blah. I couldn't read the rest, unfortunately. It sounded bad, so I ran the whole thing again. This time I didn't see the message.