[tapoxi]

I've had something similar happen. For devices that don't have or can't access GPS, they look the MAC address of nearby wifi base stations and see if anything correlated that with a location earlier. This is what the iphone did at launch with the skyhook database.

However in some cases your wifi MAC isn't unique and it'll think you're elsewhere. In my specific case it kept resetting my time zone to somewhere in Russia (I'm in Massachusetts) because that's what the MAC said.

It seems to be worse if there are no other networks in range for it to do sanity checking against.