IE loading indicator and picture buttons?

Question

HTML

Hello everyone
I made a small example to demonstrate strange behavior in IE8-9 - afternoon-river-5822.herokuapp.com/
There are two links: one opens a "fast" page, the second "slow", i.e. some calculations.
These links have two pictures: one for the normal state, the second - when the mouse cursor is hovered over.
Problem: In IE8-9, if you click on a slow link and hover over the button, the browser's loading indicator will show that the page has finished loading, but after a while a new (loading) page will still appear. In this case, if you do not move the cursor away from the button after pressing, i.e. the picture on the button will not change, then the indicator will work correctly (spin until the new page is fully loaded)
css

.b-mainmenu li {
  display: inline-block;
  text-align: center;
  vertical-align: top;
  min-width: 58px;
  height: 100px;
  margin-right: -6px;
}

.b-mainmenu li a {
  display: block;
  font: bold 11px "Lucida Grande",tahoma,arial,sans-serif;
  color: #5d5e5b;
  min-width: 58px;
  padding-top: 36px;
  background-position: 50% 3px;
  background-repeat: no-repeat;
  margin-right: 3px;
  margin-left: 3px;
}

.b-mainmenu li a:hover, 
.b-mainmenu li.active a {
  text-decoration: none;
  color: #fff;
}

a {
  display: block; width: 341px; height: 97px;
}
.b-mainmenu-fast {
  background-image: url(/assets/menu-home.png);
}
.b-mainmenu-slow {
  background-image: url(/assets/menu-backup.png);
}
.b-mainmenu-fast:hover {
  background-image: url(/assets/menu-home_aa.png);
}
.b-mainmenu-slow:hover {
  background-image: url(/assets/menu-backup_aa.png);
}

HTML

<ul class="b-mainmenu">

<li><a class="b-mainmenu-fast" href="page/fast_page">Fast page</a></li>
<li><a class="b-mainmenu-slow" href="page/slow_page">Slow page</a></li>

</ul>

How can you get around this? Or prove that this is a problem in IE and nothing can be done about it?

Answer 1

On ie8 (8.0.7601.17514) could not reproduce. After clicking on a "slow" link - regardless of the location of the cursor, the indicator shows that the page is loading. Sometimes a slow page crashes with an error.