I recently upgraded woocommerce to 1.5.8 and wordpress to 3.4.1.
On the woocommerce checkout page, after entering your address and in the boxes you select shipping information, it is blocked out as the checkout page is re-loaded.
I deactivated all plugins except woocommerce and under construction and noticed if the under construction plugin is activated, but not turned on, it creates this error.
My solution was to turn off the under construction plugin and the re-loading of a page in a page does not occur.
Recreated the error with several themes including twenty eleven.
Error occurred in Safari 5.1.5, Firefox 13.0.1