ValidationFault - usually means that some invalid data was sent to QuickBooks, and this data didn't pass validation. For example, too long value was assigned to a column. If you correct the data, the request may succeed.
SystemFault - means that something failed on the server, and it cannot be corrected by the app or developer.
AuthenticationFault - means that invalid credentials are specified in the connection string.
AuthorizationFault - means authorization failure.
Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2