Maps/satnav went crazy
 

Yesterday I loaded up Map on OS2008 to plot a route. I'm using an N800 with a Nokia LD-3W GPS bluetooth device.

It got a signal from the box, but showed me as being miles from my actual location. At one time it said I was travelling on train tracks, and another time said I was in a lake. It said kept saying I'd jumped to 200mph after travelling at 30mph!

I tried everything from resetting the LD-3W to rebooting the N800. It didn't fix it. I moved the GPS unit from the front of the car to the back, thinking it wasn't getting a complete signal. No good.

Then, about an hour later, I booted it up to give it a second chance, and it started working again perfectly.

It's always worked faultlessly until now, on many journeys.

Anybody know what went wrong? To be honest, it broke just at a critical moment when I had a really important meeting yesterday, and I need to make sure it doesn't happen again.