I have the same problem, I did the tracker reset to see if it would fix some album art issues (which it did) and I lost my contacts and text messages. It seems like its unstable now, sometimes my contacts go missing. My Music is also not accessible.... By the way, what I meant by my contacts being unstable is I can sync it back from Google but it may go missing after a reboot. If anyone knows what is going on I'd appreciate it.