Upgrading WP to 3.0.1

After upgrading to WP 3.0.1 I wrote a new post and when I displayed it, found that the sidebar widgets for that single post (the only one wrote after the upgrade) where at the bottom of the page of tat post and not at the right side as always was.
I really appreciate if you help with this.

PS. I also checked the page with editor (single.php) and the sidebar is located at SR (right side).