The first thing I'd try would be to take the SD card out and power up the device. Then On the Menu screen Settings>Screen>Where it says Start Program, choose something other than the Streets Program.
If that doesn't work, I'd install the iFly program on a new/different SD card so that Streets isn't even there. Put that in the device and power up. I would think it would give some kind of error message that it can't find Streets, perhaps it will then give you a choice on how you want the device to start.