The widget is registered incorrectly using spaces in line 136 of the plugin. This means WordPress assigns an ID to the widget which won't validate on http://validator.w3.org/
The error that is thrown says, "value of attribute "id" must be a single token" (meaning no spaces are allowed for ID's.)
This line 136:
wp_register_sidebar_widget('News announcement scroll', 'News announcement scroll', 'widget_news_announcement');
should be changed to this:
wp_register_sidebar_widget('news-announcement-scroll', 'news-announcement-scroll', 'widget_news_announcement');
to fix this problem.