Log trigger forces strange Access behaviour

[Database Administrator]

I try to log Insert and Deletes of records in a particular SQL Server 2005
table; the data is inserted or deleted in an Access continuous form (I know
that this is not state of the art, but it is a customer application and I'm
not the designer). This works fine in my environment, though for Inserts I
have to handle a form error 1029 by:
If DataErr = 1029 Then
Response = acDataErrContinue
SendKeys "{ESC}", True
Me.Requery
When I move the database and the ADP to another server, these statements
generate the messages "Another user or application has deleted this record or
changed the value of its primary key.

The associated help text makes me even more confused:
"If a parent record has a deletion trigger for child records, but does not
have any associated child records, the deletion trigger will fail and the
user will see this error. If a child record exists, the deletion trigger
functions as expected.
To correct this problem, remove the trigger from the table and manually
delete the parent record from the table. To identify the offending record,
create an SQL statement to find records in the parent table with no children
and then identify which record to delete."

I cannot find any differences in server properties, office versions and so
on. Any ideas where to start thinking?

TIA, Norbert