Odd you have the problem on all templates you've tried. Hmmmmmm.....

<script type="text/javascript" src="http://127.0.0.1:37935/xpopup.js"></script>
That has me more than a little concerned, as it has the look of a virus embed to run code against local port. It preceeds the fault and only replicates with your store, i.e. it won't replicate with mine or subtituting your template for my store.
I'm beginning a sweep based on AV reports with that Java script embed to operate against local port 37935. It looks like a Malware popup (Ad), but why only on your Store?????? Neither my AV or Firewall is giving me any alerts; so I'm not overly concerned, just cautious.
Danno