USPS plugin fatal errors

-- url of the page with the problem -- : gravestonstudies.org and amykandco.com
-- HikaShop version -- : Business 2.2.2
-- Joomla version -- : 2.5.14
-- PHP version -- : 5.4.20
-- Browser(s) name and version -- : any
-- Error-message(debug-mod must be tuned on) -- :
[09-Nov-2013 05:48:27 America/Denver] PHP Fatal error: Call to a member function xpath() on a non-object in /home3/gravest3/public_html/plugins/hikashopshipping/usps/usps.php on line 371

Hi,

I"m reposting this message: I'm getting PHP errors with two web sites when I try to purchase anything through the shopping cart. Both sites use the USPS plugin.

I first noticed the problem early this morning -- any ideas would help.