Vista - Automatically open an FTP file

Up until this morning I could automatically open Excel files stored in an
FTP site using the code below:

-----------
Dim xlApp
Set xlApp = CreateObject("Excel.Application")
xlApp.Workbooks.Open ftp://usernameassword@xxxxxx/Workbook1.xls
xlApp.Visible = True
Set xlApp = Nothing
------------

However this script has now started to return an error.

If I type in the above path in Windows Explorer, it now pops up an extra FTP
Logon window asking for my username and password again (despite these having
been entered in the path as above). This didn't use to happen. This extra
secondary login requirement is probably causing the above script to fail.

Is there anyway I can modify the above script in order to automate the
secondary login (i.e. automatically provide the username and password in the
extra FTP logon window) ?

Thanks.