It's not due to WAAS because the error occurs both when WAAS is on and
when WAAS is off.

During normal operation, NMEA transmissions occur every 2 seconds.
For those who are familiar with software programming, the interesting
thing is that the error begins at 23:59:59 GMT and normal
transmissions resume at 00:08:34. The time interval of 8 minutes and
32 seconds just happens to be 512 seconds.

Garmin has already acknowledged that it is a software problem in their
product. What we don't know is how many other Garmin GPS models have
this problem. Considering the amount of time that Garmin has taken
thus far and no fix has been posted, the error may be quite widespread
in their product line. They have a new series of Marine GPS units
that are coming out soon and maybe they are quite concerned if this
defect affects those as well.