SQL Error Accessing Object Table

Hi - I am having problems after restoring a SQL backup from a customer site. Anytime I try to change an object (import fob, create/modify/delete/compile an object) I get the following error:

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Microsoft Business Solutions-Navision

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The following SQL Server error(s) occurred while accessing the Object table:

102,"42000",[Microsoft][ODBC SQL Server Driver][SQL Server]Incorrect syntax near '?'.

SQL:
UPDATE "UnitedDB"."dbo"."Object" WITH (REPEATABLEREAD) SET "BLOB Reference"= NULL WHERE ("Type"=3 AND "Company Name"='' AND "ID"=1) AND ("timestamp"<=0x00000000E354A6F7)

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OK

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Everything else seems to be working fine.
The customer uses SQL 2000, NAV 4.0SP3. Here's what I have tried:

- Restoring the backup using SQL 2005 and 2008 (on 2 different servers)
- Ensuring the user is a dbowner
- Using both our development licence and customer licence
- Changing Compatibility Level on database
- Searching mibuso and google like crazy

Can anyone help?

Thanks,

Ryan