Reserved error -3087

I recently migrated from Access 2003 to Access 2007.  I've got a form with
a 
list box; when an item in the list box is double-clicked, another input
form 
is supposed to open for the selected item.  It worked fine in Access 2003
and 
was working fine in Access 2007; however, I just started getting an error 
that reads "Reserved error (-3087); there is no message for this error". 
I 
can't find a definition for this error anywhere.  My On Dbl Click code 
follows:

Private Sub MsnNumList_DblClick(Cancel As Integer)
On Error GoTo MsnNumList_DblClick_Err
'Open input form for selected project'

    DoCmd.OpenForm "InputTARInfoForm", acNormal, "", 
"[MissionID]=[Forms]![Select Mission Number for TAR Info]![MsnNumList]", ,

acNormal

MsnNumList_DblClick_Exit:
    Exit Sub

MsnNumList_DblClick_Err:
    MsgBox Error$
    Resume MsnNumList_DblClick_Exit

End Sub