Standard troubleshooting steps:
1. Deactivate all plugins. If the problem disappears, reactivate plugins one by one - checking the problematic sections after each reactivation until you find the culprit.
2. Switch temporarily to the default theme to rule out any theme-related issue.
If none of the above helps, you need to look at the last things added to the blog. Your last post, for example, contains some odd characters/spacing that make me think that the content has been pasted in from somewhere other than a plain text editor.