Keep getting IDENTITY_INSERT error

I keep getting an error that states I cannot insert explicit value for itentity column in table 'Users' when IDENTITY_INSERT is set to off, can anyone help?

Code:

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/****** Object:  Table [dbo].[Users]    Script Date: 5/6/2010 10:48:47 AM ******/
if not exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[Users]') and OBJECTPROPERTY(id, N'IsUserTable') = 1)
 BEGIN
CREATE TABLE [Users] (
        [UserID] [numeric](18, 0) IDENTITY (1, 1) NOT NULL ,
        [NTAccount] [varchar] (100) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL ,
        [Active] [bit] NULL ,
        [UserChanged] [bit] NULL ,
        [UserAgreeDate] [datetime] NULL ,
        [AFSC] [varchar] (10) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,
        [AFSC2] [varchar] (10) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,
        [DutyTitle] [varchar] (50) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,
        [UserName] [varchar] (50) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,
        [Password] [varchar] (50) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,
        [GroupID] [int] NULL ,
        [FirstName] [varchar] (50) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,
        [LastName] [varchar] (50) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,
        [NickName] [varchar] (50) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,
        [LastLogin] [datetime] NULL ,
        [WingStructure] [varchar] (100) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,
        [BioImage] [varchar] (50) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,
        [LongDistancePIN] [varchar] (10) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,
        [MilitaryRank] [varchar] (100) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,
        [OfficeExtension] [varchar] (3) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,
        [SmallImage] [varchar] (100) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,
        [OfficeFAX] [varchar] (3) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,
        [WorkStatus] [varchar] (50) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,
        [IsAdmin] [bit] NULL ,
        [LastUpdate] [datetime] NULL ,
        [EMailAddress] [varchar] (100) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,
        CONSTRAINT [PK_Users] PRIMARY KEY  NONCLUSTERED
        (
                [UserID]
        ) WITH  FILLFACTOR = 90  ON [PRIMARY]
) ON [PRIMARY]
END

GO

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