Open the form modally.

docmd.OpenForm "frmHi",,,,,acdialog

This causes code execution to halt until 1) the form is closed, or 2) the
form is made not visible.

David Atkins, MCP

It sounds as though you need to open frmCompareMethod in dialog mode.
When you open it, use something like

   DoCmd.OpenForm "frmCompareMethod", WindowMode:=acDialog

That will cause the calling routine to wait until the form is closed
or -- and this is the key -- hidden.

Then, when the user makes a choice frmCompareMethod, hide the form by
setting its Visible property to False:

   Me.Visible = False

At that point, your calling code will resume, and can pick up the chosen
method, close frmCompareMethod, and proceed to compare the files.

The calling code might look roughly like this:

'----- start of example code (air code) -----
   Dim intMethod As Integer

   DoCmd.OpenForm "frmCompareMethod", WindowMode:=acDialog
   ' Is the form still open?  If it's closed, we'll assume the user
wanted to cancel.
   If CurrentProject.AllForms("frmCompareMethod").IsLoaded Then
       intMethod = Forms!frmCompareMethod!optCompareMethod
       DoCmd.Close acForm, "frmCompareMethod", acSaveNo
   Else
       MsgBox "Comparison cancelled."
       Exit Sub
   End If

   If intMethod = 1 Then
       ' Do Method 1
   Else
       ' Do Method 2
   End If
'----- end of example code -----

Thanks alot for your help.  Works great!!

Brian