This is a very common problem with the boost 5.0 os for the 8330.
I suggest heading over to the Nathanix Blackberry Resource - Home of the Hybrids forums and installing their latest hybrid. Its faster more stable and has far far FAR less problems then the stock boost os. So go ahead and check it out, I promise you'll never regret it!
Posted from my CrackBerry at wapforums.crackberry.com