Motorola E815 / E816 Hollywood

i have an 815 and my problem started about 3 months ago.... my phone likes to restart itself for no reason mostly after i get about 20 text messages i go to respond to one and it freezes and restarts. i have had 3 replacement phones now and they all hae the new software in them. i even called tech support to see about fixing it they have no idea eityher they tried giving me a new authentication key but that hasnt helped either.... someone help please!!!