In response, Twitter shut down the application's access to tweets for about an hour Wednesday while fixing the problem.
The two-line message was automatically "retweeted," or sent out again, when received by TweetDeck, a computer application for Twitter's power users. Affected tweeters saw pop-up windows on their screens. The tweet was sent out tens of thousands of times, but left its victims otherwise unharmed.
Twitter initially told TweetDeck users to log out and log back in. When that proved ineffective, it shut down the application's access to tweets. Twitter was still accessible through its website and through other applications.