access errors after SP3 install on access XP

[Roger]

I have a delete button on my form that runs the code listed below. It
worked fine until i installed service pack 3. I get a run-time error
2105 message.
This database is used daily in our office and i am desperate to find the
solution. I have played with different refernces and re registering
them to no avail. selectclass and LookForRecord are cascading
comboboxes used to select a single record for display in my form.

Code:
Private Sub Delete_Click()
On Error GoTo Err_Delete_Click

DoCmd.DoMenuItem acFormBar, acEditMenu, 8, , acMenuVer70
DoCmd.DoMenuItem acFormBar, acEditMenu, 6, , acMenuVer70

Me!LookForRecord.Requery
Me!LookForRecord = Null
Me.DataEntry = True
Me!selectclass.Enabled = True
Me!LookForRecord.Enabled = True
Me![LookForRecord].SetFocus

Exit_Delete_Click:
Exit Sub

Err_Delete_Click:
Me!ClassNumber.SetFocus
Resume Exit_Delete_Click
End Sub