Prevent broken html

Is there any way to prevent FCKeditor to be used to break html code? I mean, if someones just writes "</td></tr></table></td></tr></table>....", when I print that in my website, it breaks the layout.

[*]Should I deactivate the html source code? How?
[*]Should I check for any unclosed tags before inserting it to the database? How?

Any other ideas?


Thanks,
Fernando.