Domain unavailable after update to version 1.1

Hi!

Since the update earlier today, I cannot open my website if I enter the URL without the leading “www”:

http://www.spanishplanet.de (works fine)
spanishplanet.de (error message)

The error message displayed in the browser says:

Warning: Cannot modify header information – headers already sent by (output started at /var/www/web75/html/wordpress/wp-content/plugins/recent-tweets-widget/widget.php:240) in /var/www/web75/html/wordpress/wp-includes/pluggable.php on line 876

How can this be fixed? Thanks for your help!

Daniel

http://wordpress.org/plugins/recent-tweets-widget/