This was driving me nuts. I had started using the quick key 'Q' to switch profiles from Normal to Vibrate and after doing so, the phone would always default back to Vibrate Only on reboots. After searching around, it appears they identified the same issue on Crackberry and it appears to be related to the 'Q' shortcut. Once I changed the profile by clicking the speaker (not using the 'Q'), it then rebooted in normal mode. Not sure if this has been fixed in a later OS release as I'm still on .254 but thought it was interesting to point out as it's a definite bug.
Sound Profile defaults to Vibrate on Reboots - BlackBerry Forums at CrackBerry.com
Sound Profile Defaults To Vibrate On Reboots 
Re: Sound Profile Defaults To Vibrate On Reboots 
