My Heart is A-Twitter Rated 5 out of 5 stars
This has become my single most valuable add-on, especially because it works in both Firefox and Google Chrome. Alas: out of the blue, beginning this afternoon, it no longer checks Twitter. Clicking on the Twitter link opens Twitter successfully, but the link is grayed out, and the count of unread Twitter messages no longer appears. Same problem in both Firefox and Chrome. Perhaps it's time for an update to the Twitter script?
Amended 12 June 2013: Bingo! The new Twitter script dated 12 June 2013 fixed the problem. Many thanks for your prompt response.