I am running a pixhawk with copter 3.3.3 which seems to have been working ok. However today whilst doing a few tests outside I have been getting pre-arm GPS errors. I have had both GPS speed and horiz errors but mainly speed. Occasionally I can get it to arm ok in loiter but most times I get the above errors. In all cases my hdop is around 1.0 with 6+ sats on both gps units. I am hoping someone can come up with some suggestions as to what may be causing these errors.