An update on this, it's now failing with the message:

Error 544 - [Microsoft][ODBC SQL Server Driver][SQL Server]Cannot insert
explicit value for identity column in table 'zstblApplicationFunction' when
IDENTITY_INSERT is set to OFF. (ODBC.QueryDef)Error 3146 - ODBC--call
failed. (DAO.QueryDef)

In Profiler, the SQL trace shows:

<---------------------------------------------------
SET IDENTITY_INSERT "dbo"."zstblApplicationFunction" ON
go
exec sp_executesql N'INSERT INTO "dbo"."zstblApplicationFunction"
("ApplicationFunctionID","SortOrder","ParentApplic ationFunctionID","Applicat
ionFunctionName","DisplayName","Hyperlink","FormHe lpID","IsMenuItem","IsSubM
enuItem","IsEnforced","SysIsInsert","SysIsSelect", "SysIsUpdate","SysIsDelete
","SysIsExecute") VALUES
(@P1,@P2,@P3,@P4,@P5,@P6,@P7,@P8,@P9,@P10,@P11,@P1 2,@P13,@P14,@P15)', N'@P1
int,@P2 int,@P3 int,@P4 varchar(50),@P5 varchar(50),@P6 varchar(8000),@P7
int,@P8 bit,@P9 bit,@P10 bit,@P11 bit,@P12 bit,@P13 bit,@P14 bit,@P15 bit',
1, 3, NULL, 'SECURITYMENU', 'Security', NULL, NULL, 1, 0, 0, 0, 1, 0, 0, 0
go
IF @@TRANCOUNT > 0 ROLLBACK TRAN
go
---------------------------------------------------->

If I copy and paste that into Query Analyser it inserts the record. When
Access issues these commands to the server it fails. Odd.