I was having this problem previously. I realized that when I synched using the USB (for Address Book), I got the time that was on my PC. My PC time is wrong b/c our server is wrong. Big domino effect there. Don't know why the BB would pick up the PC time. It did this regardless of the setting for Source. I have since gotten the server time corrected and have no issues.
Thanks JSanders. My initial thought was - "wow, how did I miss that?". I went to DM and realized it was already unchecked. So, either I did that before when I was having issues and forgot, or it was always off and I had some other issue. I can't tell anymore b/c our server time is now correct.