(warning, VBA newbie....)

I  have a macro which has been working fine when run in PP 2003 but is not
working in PP 2007.  I'm trying to insert an image onto a slide, the image is
on a web server so I have something similar to the following code:

ActiveWindow.Selection.SlideRange.Shapes.AddPicture(FileName:="http://webserverhost/images/image1.gif",
LinkToFile:=msoFalse, SaveWithDocument:=msoTrue, Left:=323, Top:=233,
Width:=75, Height:=75).Select

In PP 2003, it works fine, the web image correctly gets displayed on the
slide.
In PP 2007, I get a 'Error -2147024809: The specified file wasn't found'

If I 'manually' insert the pic in a slide, by choosing Insert->Picture and
then specify 'http://webserverhost/images/image1.gif' as the filename, the
image shows up in the slide as it should. In otherwords, if i don't run the
macro and do it by hand in PP, it works.

I'm not sure what is going on. Is there something new in PP 2007 that is
preventing images from a web server (which in my case happens to be on the
local machine, so it's an internal web site) being added to a slide?

Thanks in advance for any help!

-BP