Commenting in html code may make a web page renders the wrong way,
The problem i faced is if you wrote:
<!-- some comments <!-- another some comments -->
Not all HTML parsers get this right, so my problem was that the VS and dream weaver consider it as comments but in the browser i saw "some comments, hello-->" showing, so the browser didn't consider it as a HTML comment, so take care from this point.
See some more hints about html comments