are you using firefox and yahoo?
Error type : UDB:1 how to fix this? - Yahoo! Answers
Can be done from Firefox, "Tools, Privacy, Show Cookies. Look down the list and select those associated with Yahoo. Delete them and restart browser.
From IE, Tools, General, "Browsing history" Settings, View filesl...
Then, find the cookies related to Yahoo, select, right click and delete.
Restart browser.
Hope this helps
Hardwired
also see the "how to remove / fix the firefox cookie database on this forum:
http://www.emailquestions.com/yahoo-mail/265-yahoo-mail-does-not-remember-my-password.html