My 6 month old Tilt displays 4 horizontal colored bars and locks up when I press the power on button. After several cycles of removing and reinstalling the battery and pressing the power button it eventually comes around. The phone will work until I have to turn it off again but won't sync. Last time this happened the tech in the AT&T store replaced the sim card and its been fine for 5 weeks but now it's doing exactly the same thing again. Is it time to call for a replacement or can someone suggest another fix? I can't believe that the sim card is actually the problem here.