HTC Hero :: Phone Restored Itself To Factory Settings - All Stuff Gone

I got a new Hero about a month ago. Last weekend, it basically restored itself to factory settings. All my contacts are gone, all the apps I downloaded had gone, text messages, calendar, the lot. It was as if I had pushed a button and reset the phone. Now, little by little, stuff has come back. I logged back into my google account and I would assume the calendar syncs with the google calendar as all my appointments are back. The Google account also remembered which apps I had and I redownloaded them. However, the contacts and the text messages have never come back. Is this a known issue? Is my phone possibly faulty and needs to be returned? I'm so confused. I do love this phone but I am not putting up with a phone which I cannot rely upon.