Just FYI any of you that experience this, I still do to this day despite upgrading several firmware versions. I'm currently running 2720 to my knowledge after a visit to Stu I've simply learnt to live with it I'm either still getting it because I'm terribly unlucky, or I've permanently had a faulty RNS unit or even antenna(?). Either way, I've not pursued it any further.Don't be surprised though for it to still affect you once changing firmware/map versions if your unit's anything like mine
