I've used Shake to Answer by Murat Yener for two years on my Droid X and had no problems with it. I recently upgraded to a Razr Maxx and installed it on that phone. I was having two serious problems recently:
1) when talking on the phone, the Mute and Speaker would spontaneously activate and could not be turned off.
2) the Voice Command would also spontaneously ask me to say a command, and it was very difficult to turn it off. I did a factory reset to try to fix these problems, but only removing Shake to Answer did the trick! It's only been a day without these problems, but thought you Maxxers might want to be aware of this. Anyone else having these issues?