I think at this point you'd be better off doing an Archive & Install with the Preserve Users and Network Settings option. Read this before you do that:
http://support.apple.com/kb/HT1545
That will replace the OS with a fresh copy, while leaving all your programs, accounts and other files untouched. Then you can install the 10.5.8 Combo Update, use Software Update to get any other updates you might still need, then Repair Disk Permissions, delete the Previous Systems folder, restart your Mac and try Safari again.