I've been having problems with PC over the past couple of days. It seemed to start with 0.5.4, when using the new URL brought me to the main MTurk web site, with a message saying "no HITs match your criteria" and the term "pandacrazy=on" filled in in the search field.
Last night I updated to 0.5.6 and it started working again! Today, after auto updating to 0.5.7, it's stopped working again.
Hoping that helps someone understand what's going on. Love this script!