From the GPS World web site:

http://gpsworld.com/cgsic-issues-notice-on-problem-with-certain-gps-devices/


May 15, 2014

Recently, many GPS users have reported intermittent GPS outages in
their devices. After investigating, the U.S. government has linked
the problem to flawed processing of GPS satellite data within certain
GPS receiver chipsets. The GPS satellite service continues to
function as designed and is fully operational and available worldwide.

The problem affects only user equipment that erroneously ignores the
satellite health status information broadcast from every GPS
satellite. The problem is not related to the April 28, 2014,
activation of civil navigation messages on the GPS L2C and L5 signals.

Since March 15, 2014, the Air Force has been conducting functional
checkout on a GPS satellite, designated Space Vehicle Number (SVN) 64.
SVN 64 broadcasts a data message that clearly indicates SVN 64 is
unusable for navigation. Nevertheless, the U.S. government has
confirmed that certain GPS receivers are using data from SVN 64, in
violation of GPS interface specifications, resulting in outages or
corrupted, inaccurate position calculations.

The Air Force testing is scheduled to end in mid-May 2014 at which
time SVN 64 will begin normal operation. At that point, these
problems may stop occurring. Meanwhile, the U.S. government urges all
GPS device makers to review their products for compliance with the GPS
interface specifications, and if necessary, to issue software/firmware
updates to users as soon as possible. View specifications.

Users experiencing GPS outages should check with their device
manufacturers for available software/firmware updates. In addition,
any civil user seeing unusual behavior in GPS user equipment should
report it to the U.S. Coast Guard Navigation Center (NAVCEN). Aviation
users should file reports consistent with FAA-approved procedures.
Military users seeing unusual behavior should report it the GPS
Operations Center (GPSOC).

Please direct any civil user questions to NAVCEN at (703) 313-5900,

http://www.navcen.uscg.gov