I'm having a different problem: when clicking on the "View Details" link in Google Earth, an error message is displayed saying that the key being used was registered for a different site.
The problem seems to be the URL being generated by the Google Earth .kmz file is wrong, and contains "geocaching.com//seek/..." rather than "geocaching.com/seek/...". Should be easy to fix, but it's quite annoying getting an error on every link.