Please sign in again. iTunes Match has encountered an error; how to fix

Several users have reported that they received the following error message when they launch iTunes and try to update iMatch running on Windows OS:

Please sign in again.

iTunes Match has encountered an error.  Please choose Sign Out and then Sign In from the iTunes Store Menu

Fix:

1. Right click on your iTunes icon and click “Run as administrator.”


2. When iTunes is running, sign out, then sign back in.


3. De-authorize the computer, then authorize again (Store > Deauthorize This Computer and then Store > Authorize This Computer)


4. Turn on iMatch


5. Close iTunes and reopen without “Run as administrator”