Safari quits unexpectedly few times a day!

My Safari quits unexpectedly few times a day! Please help. I already reinstalled safari, it didn't help. Here's the message it sent to Apple.

Date/Time: 2012-11-16 16:52:23 -0800

OS Version: 10.5.8 (Build 9L31a)

Architecture: i386

Report Version: 4

Command: Safari

Path: /Applications/Safari.app/Contents/MacOS/Safari

Version: 5.0.6 (5533.22.3)

Build Version: 3

Project Name: WebBrowser

Source Version: 75332203

Parent: launchd [115]

PID: 37607

Event: hang

Time: 10.58s

Steps: 1