I have the moto droid. My default sms messengs app crashes several times a day. When this happens all my threads and messages are deleted. When I open the app it will say not responsive and I have to force close. If I try to open the messages app again I get the force close screen and must turn my phone off and back on. This happens several times a day and can't be good for my phone. I have the free antivirus installed and it says my phone is very clean so what could cause this?