What do you do if you receive this error when trying to tweet or retweet and no new tweets are arriving?
A protocol error has occured. Code 401: Could not authenticate with OAuth
This is an authentication error, so a new token must be generated to re-authenticate with Twitter.
To do this, you must remove you account (Dashboard, long press on affected account, select Remove) and then add it back. Once you've done this, the error should disappear.