IPhone :: 3GS With IOS4 / Locking Up / Freezing & Dropping Calls

We have two iPhone 3GSs in the household, my dads and my moms.I installed iOS4 on both. And both seem to freeze, lock up, drop calls, have occasional weird glitches far more frequently than they did on 3.1.2 (3.1.3 caused issues as well but not as frequently as on iOS4) Sometimes, the lock screen doesn't unlock and the my slide to unlock it isn't recognized (fixed by hard rebooting the phone).

One time the phone froze completely on the Contacts menu.I'm wondering if the proximity sensor might be glitching and causing some of these dropped calls as well.iOS4 is awesome, don't get me wrong. But my parent's getting glitches is annoying as hell. They were hesistant about going with a smartphone instead of a simple flip phone already, and this isn't helping. Is anyone else having these issues or similar ones?Did Apple screw the pooch when it comes to bug testing the new OS?I wish Apple would just let us go back to 3.1.2 on our iPhones. That worked flawlessly where as the subsequent versions all have serious issues.