So on the Emmet plugin I do this sequence of commands:
type:
header.main-header
(Press Tab) you get:
<header class="main-header"></header>
type (between the header tags):
h1.main-title
(Press tab) you get:
<h1 class="main-header><h1 class="main-title"></h1></header>
As you can see it changes the <header tag into an h1 as well, breaking the code.
But I'm not really sure if this has to do with IceCoder or Emmet. Bit like I said, it only happens on Emmet for IceCoder.
Cheers,
Brian