Download the app "GPS Test" from the market (Play Store) it is free, then goto settings and clear AGPS data, then update AGPS data. Sounds like it may be corrupt or lost. Mine did the same thing, this fixed it. Probably any GPS app will do this, but this one is free and makes it easy, buttons to clear and update are clearly marked right at the top of the settings page takes all of 10 seconds to fix, and my GPS fix location in less then 30 sec. now.