I just got my Droid a few days ago and have noticed a weird problem. Today I was at the unlock screen just about to unlock my phone when a phone call came in. The phone just started vibrating, but the ringtone wasn't going off even though the phone wasn't on silent. No incoming call window to tell me who was calling, nothing in the notification bar. The phone didn't switch over to voicemail and continued to vibrate. The screen became unresponsive (I couldn't slide to unlock) and none of the buttons did anything to either stop the vibrating or otherwise. I had to pull the battery to get it to stop. Once it restarted, the voicemail and missed call notification showed up. It also happened once when I was in the web browser. More or less the same thing, but I could still use the phone. The ringtone was going off and the phone was vibrating, but the incoming call window did not show up nor was there a notification in the notification bar. I was even able to open the phone app and use the keypad and anything else. Eventually I restarted the phone and when it finished restarting, the missed call info and voicemail notification was in my call log. I know the phone can't do data and voice at the same time and there have been times that I've been in an app or the browser and the incoming call screen comes up and it works fine.
Has anyone had this problem before? My phone is not rooted or modified in anyway and is more or less just as it was when it came out of the box.