Has anyone noticed their RNS510's GPS playing up in thundery conditions?

Heading from North Kew to Balwyn shopping centre this morning I thought to set up the GPS (not because i don't know the way, but to pinpoint the street number in what's usually heavy traffic.)

The thing went mad — it kept insisting on wrong turns, U-turns, roundabouts where there were none etc.

When I got to the Balwyn Road intersection it wanted to turn me back toward home, and hadn't a clue where it was.

A newcomer to Melbourne would probably have been thoroughly lost.

Parked, did what I came to do, and when I restarted the car it was fine — posted the name of the side street I was in and all.

Let it guide me home and it was spot on.

Probably unrelated, but when I came back to the car both rear indicators were out and I had to drive home from Balwyn without them — got tooted a few times...

Pulled all fuses in the dash, found them intact, put them back and all was well again — most likely just a corroding fuse leg or holder, which at less than 3 years old doesn't bode well for the long term...