Unknown error keeps popping up across all my machines. This is a complaint that seems pretty common and there is a magic key incantation to help...This seems to do a complete delete of all the iTunes Match data, so hopeing that it helps!
Welcome to iTunes Store Customer Support. My name is XXXXX.
I understand that you received the error 4010 while using the iTunes Match. I know how eager you are to get this issue resolved. I will do my best to assist you in resolving the issue.
XXXXX, there is something I would like you to try which will solve the issue:
1) Open iTunes
2) Open Store Menu
3) Hold down Option key on your Keyboard and click "Turn off iTunes Match"
4) Then again open the Store Menu and click on "Turn of iTunes Match"
If the issue still persist please reply back with the screenshots of the error received.
Thank you for your patience while we work together in resolving this issue. I hope you have a great day!
And then there are some other tricks that are variants
The only think I can suggest is something you may have tried already: Turn off iTunes Match in the Store pull-down menu, then turn off Genius in the Store pull-down menu. Wait until the Genius info is deleted. Quit iTunes. Restart iTunes, turn Genius back on from the Store menu, and go through the steps to set Genius up. Let Genius completely go through the setup process, and then turn iTunes Match back on. Go through the steps to set up iTunes Match and wait.