Yes, using the Seek method on a DAO Recordset will not work after splitting,
because the Recordset of an attached table is dbOpenDynaset, whereas the
Recordset of a local table defaults to dbOpenTable. The simplest way to work
around this is to explicitly open a dbOpenDynaset in your code, and then it
will work correctly after split, i.e.:
   Set rs = db.OpenRecordset("Table1", dbOpenDynaset")
Better still, use a SQL statement so the recordset contains only the fields
and records you really need, and is sorted as desired. This is generally a
more efficient approach than Seek.

The other important point is to check that the data is available when the
database starts. After splitting, it is always possible that the data is no
longer in the same folder, or the server name has changed, and you need to
reconnect. For an example of how to do that, see the refresh module in
solutions.mdb, downloadable from:
http://msdn.microsoft.com/library/officedev/bapp2000/mdbdownload.htm