Errors using remote access and changing permissions

[Mikecl]

I have a SBS2003 server however the change user permission wizard complains about setting rights on the sharepoint site (0x8102004a) failed to add user, plus error 0x800004005 failure to set properties on the account.
Also when using OWA you get error messages access denied or unknow symbol when tring to send an email, outlook appears to work ok.