Help Incoming call lag/freeze

[Manbartz]

I love my atrix, but recently when I have an incoming call, 10% of the time I wont be able to answer it because i can't slide the locker to answer, literally nothing happens. It just rings, says who is calling, but I can't answer it because the phone is frozen. This rarely happens, but I can only imagine this happening when I really need to answer the phone. If anybody has any advice or pointers that would shed some light on the situation, it would be grateful.