we've worked successfully with social zimlet and twitter, even with two twitter accounts. Since one ore two days, we get the following message in Zimbra (browser-pop-up):

https://zimbraserver requests a user name and password. Output of website "Twitter API"

(tranlsated from German).

It doesn't matter if I enter the zimbra or twitter credentials, it appears again. If I click cancel, the following error appears as zimbra message:

"Twitter Error: Timestamp out of bounds"