Motorola Droid Bug with Calls

Sometimes my Motorola Droid has a problem with calls. What happens is that I either answer or make a call. Then, when the screen blacks out, as it should, it is tricky to press any buttons afterwards. The screen will flicker on after tilting the phone, only to turn right back off. I don't dare switch to another application, because then I can never get back to end the call. The only recourse I have seen is to put it in speaker phone mode, because that changes the display setting.