From NEI Training and Technical Support Manager Eric Bock:
Earlier today we became aware of a problem downloading CORS base station data from the NGS/NOAA servers through Trimble Positions Desktop add-in. At the beginning of post processing, you will see error messages for the failed downloads. We are currently investigating the issue but it appears to affect Pathfinder Office and Field Inspector in addition to Trimble Positions. One workaround would be to note the URLs for the attempted downloads and then download the files manually through a browser. You can then setup a new post processing profile for those specific files.
We’ll share additional information as we have it.
http://positionsblog.trimble.com/?p=223
Update: 10:00 AM – Work-around solution can be found by downloading this pdf: Downloading Base Station Data directly from NGS