encyclo - 11:11 pm on Jul 5, 2010 (gmt 0)

If you're talking about this trailing slash (in red):

<link rel="canonical" href="http://example.com/index.html"/>

Then you should not be using it unless you're using XHTML syntax in your markup. (Note also that this would not then be the same issue as the original poster above.)

Also, in your example, it is unlikely that your canonical URL would include the "index.html" part, and you may need a "www" in the URL too. So tread carefully so as not to create problems for yourself - first decide what the canonical link for the page should really be.