Spectra / Ashtech has released a mandatory firmware upgrade to be applied prior to midnight UTC this last day of June.
Evidently the existing internal RINEX converter that generates standard RINEX files in the receiver, which are then archived at NGS CORS, will not survive the leap-second change added at midnight.
PLEASE CHECK HORZ and VERT COORDINATES AFTER THIS FIRMWARE UPDATE! Normally I setup a couple of receivers on control and verify coordinates when I make changes. Unfortunately I am in Boston and won't be able to check in.
I am going to keep the existing historic position after the firmware upgrade. The plan is to change to the new NGS provided coordinates (in the NAD 83(2011,MA11,PA11) epoch 2010.00 frame) when the transmit radios are narrow-banded around the first of August.
If you are not already aware, NGS finished updating all control points in the new NAD83 frame on Friday (or today Saturday). 
If there are any problems, I will let you know.
Cross your fingers and have a great 4th of July!
Mark Silver