I was performing some testing, so I commented out a bit of my ASP.NET markup with <!– –> because, after all, I’ve used that for years, right?  Well, it took me just a sec to figure out that the server control was still being executed and that the <!– was just rendered before it on the client.  The important bit:  <!– is HTML syntax, not server-side syntax.  If you want to comment out a server control, use the following syntax:

<%–   <asp:Button . . . . />  –%>