Rendering old pages randomly....

Attached are 2 versions of the home page, both rendered using Firefox within seconds of each other.
The are very different, as one represents the code as it was around 2 yesterday afternoon, the other is the code as of 5 PM yesterday. I can see the difference in firebug:
the two oclock version is:

<div id="logo-area" class="col4">
<a href="http://thestrapsaver.com">
<img class="trueleft col4 logo-top" alt="The Strap Saver Logo" src="http://www.thestrapsaver.com/wp-content/uploads/logo.png">
</a>
</div>

the five oclock version is:
<div id="banner" class="row">
<div id="logo-area" class="col12">
<a href="http://thestrapsaver.com">
<img class="trueleft logo-top" alt="The Strap Saver Logo" src="http://www.thestrapsaver.com/wp-content/uploads/logo990.png">
</a>
</div>

note that the image used for the logo is different as well. These screen shots were taken seconds apart. and if I render the pages again, I may get one or the other. The code in question is from the header.php template and the home page uses a custom template, assigned to it. The custom template was created by copying page.php, removing the sidebar widget and adding three widgets/columns at the bottom of the page.

Yes, I have cleared cache, many times, yes, I have contacted my hosting provider to report problems (they see none.) Yes, there is only one page named "home" and yes it is assigned to custom-home.php

Has anyone ever seen anything like this before?