I thought I saw a post a while back about my issues but can not seem to find it.
A few of my Unity 4.0.3 Unified Message Users playbackack their messages in their outlook and it sounds like it is in fast forward mode or they kind of sound like a chipmunk. (Excuse my description, I sound like my wife when she is describing a problem.)
It only happens from outlook, when you listen to the message from the phone itself it sounds fine. It happens from both PSTN callers and internal IP Phones.