IPhone 3GS & 4 verifies account but wont sync, another account syncs ok but not the calendar!!

I’ve got a std server running SBS 2003 SP2, and exchange SP2, very strange things are happening:
When I create a brand new account, this account plus existing ones will not sync, tried recreating the virtual directors, turning on and off form based and ssl, the really weird thing is its fine with one of the user accounts except it won’t sync the calendar aspect!!  I’ve tried users with admin rights; I’ve played around with IIS setting recommended by several websites.  The server is running on 2 network cards for lan and wan.  The server developed a fault with their hard drive array, very long story but in the end Exchange had to be re-installed and all emails imported back in.  The service pack has been re-installed. The event log comes back with a 3005 error, I've also ran 'AS tester' app on the iphone, that comes back with 'Activesync is not available, activesync detected, but access denied. HTTP403: Disabled for this user'!!!! It makes no sence, help!!