hi ! have problem re " where to " function with my nuvi 750.had use this unit abt 4 days. it had worked the first 2 days. yesterday , it hanged, after resetting it, the "where to" function , the screen reads " cannot calculate route no roads at starting point". 1 time it started calculating, then it hanged again. Same result after reset again. May i know if someone has encounter same problem ? tnx !