User-Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; WOW64; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; CMDTDF; InfoPath.2; .NET4.0C) Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.13) Gecko/20101203 Firefox/3.6.13 (.NET CLR 3.5.30729) when firefox encounters a single html comment line, it block comments all the subsequent html code untill the next single comment. like <!--my comment --> <div> } <p>......</p> } <--- Ignored or block commented by firefox </div> } <!-- my next comment --> Reproducible: Always Steps to Reproduce: 1.Add single line html comment line between any html code. 2.Add another anywhere after it 3. Actual Results: The html code between the single comment lines are block commented out Expected Results: firefox should only comment the code that is between <!-- --> the workaround that i use for this is <!---------------> <!--my comment --> <!---------------> <div> } <p>......</p> } <--- Not Ignored or block commented by firefox </div> } <!---------------------> <!--my next comment --> <!--------------------->

This is expected see http://www.w3.org/TR/html401/intro/sgmltut.html#idx-HTML for rules on parsing comments.