Setting a blog's timezone to America/Sao_Paulo may cause errors in the new version of Blogger and on Blog*Spot. This is due to daylight saving time changes that lead to Sundays without midnights in the timezone. Other timezones that have Sunday-at-midnight daylight saving time changes will be similarly affected. Until we fix this, the workaround is to use a different timezone. Update, 12/4: This has been fixed. Please contact Blogger Support if you see any other timezone problems.