?
the FileDialog isn't used to save your textfile.
It is merely used to retrieve the textfile the user needs to select, to
write the results of the formfields to.
At least, this is what understood from yr initial post.
(If this assumption is not correct, than correct me :-)

I've combined my proposal to yr initial post, see below code.
Try the code, and pls check whether formfields data is actually written to
(and saved in) the textfile?

' Here is the code
Dim tempFile
Dim fd As FileDialog
Dim oFF as formfields
Dim i as integer
set oFF = activedocument.formfields

i = FreeFile()

Set fd = Application.FileDialog(3)
fd.Filters.Add "Text Files", "*.txt"
fd.FilterIndex = 0
fd.InitialFileName = "U:\History"
fd.AllowMultiSelect = False
If fd.Show Then
   tempFile = fd.SelectedItems(i)
   Open tempfile For Output As #i
   Write #i, oFF(5).Result, oFF(6).Result, _
       oFF(7).Result, oFF(8).Result, _
       oFF(9).Result, oFF(10).Result
   Close #i
End If

The code in words: FileDialog retrieves the name of the target textfile
selected by user.
The name of this textfile is used in the Open ... For Output command to open
an I/O channel to target textfile, using #i (retrieved by FreeFile function)
The results of the FormFields (5, 6, 7, 8, 9 and 10) are written to the
target textfile.
Data is written to textfile, so the I/O channel can be closed. If no errors
occur, all data is saved to this textfile ...

--
Krgrds,
Perry

System:
Vista/Office Ultimate
VS2005/VSTO2005 SE