Someone Else Editing Record ? Only Me On The Server ?

I have some software (written in Delphi 5) which has been working for
several months without a problem.

I have been given a copy of the database on our development server
(SQL 7) and have pointed the software to this. So, nothing has changed
with the software. In theory the servers should be the same.

However, if I try to make a small change to any record (as I would on
the 'live' system), I get an error stating that another user is
editing the record. Now, I'm the only person with access to this
server. So am I stopping myself I wonder ?

If I create an ODBC connection to the database through Access 2000, I
get the same error. I feel I can reasonably assume that the software
is not at fault.

I'm sure it's something SQL based, whether it's an error or
configuration difference, but I'm stuck.

I've checked who is locking/blocking, and yes it will show me as
having the record open, but this is me attempting to edit the record
so I would expect this.

I can edit the table directly in SQL, but it takes 30 seconds or more,
freezes EM and then allows the change. Table info below :

if exists (select * from sysobjects where id =
object_id(N'[dbo].[PostReceived]') and OBJECTPROPERTY(id,
N'IsUserTable') = 1)
drop table [dbo].[PostReceived]
GO

CREATE TABLE [dbo].[PostReceived] (
[PostID] [int] IDENTITY (1, 1) NOT NULL ,
[Type] [varchar] (100) NULL ,
[ClientsName] [varchar] (100) NULL ,
[DateReceived] [datetime] NULL ,
[EnteredBy] [varchar] (100) NULL ,
[AssignedTo] [varchar] (100) NULL ,
[DateAssignedTo] [datetime] NULL ,
[Adviser] [varchar] (100) NULL ,
[TargetDate] [datetime] NULL ,
[CompletionDate] [datetime] NULL ,
[Completed] [bit] NULL ,
[KeyAccount] [varchar] (100) NULL ,
[Notes] [text] NULL ,
[Specific1] [varchar] (20) NULL ,
[Specific2] [varchar] (20) NULL ,
[Specific3] [varchar] (20) NULL ,
[Specific4] [varchar] (20) NULL ,
[Specific5] [varchar] (20) NULL ,
[ToDelete] [bit] NULL ,
[EnterUser] [varchar] (20) NULL ,
[Returned] [bit] NULL ,
[ReturnDate] [datetime] NULL ,
[ReturnReason] [varchar] (87) NULL ,
[PrintAdviser] [bit] NULL ,
[EmailAdviser] [bit] NULL ,
[EmailSM] [bit] NULL ,
[EmailRegionManager] [bit] NULL ,
[ReturnText] [varchar] (150) NULL
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]
GO

(Yes I know about using Identity in the key, but it's on my list to
change before anyone says anything).