clean and simple rom problem

[mikebro]

About 5 times a day when my phone rings it will not let me answer it. I can hit the answer button and it does nothing. I can hit end and it starts ringing again and shows unknown on the caller id. I then soft reset it and it works for the next couple of calls. The problem is I never know when it is messing up until it rings then can't answer it. Suggestions????