prueba con esto:
Código:
Dim url As String = "http://www.forosdelweb.com/images/vbulletin3_logo_fdw.gif"
Dim miRequest As System.Net.WebRequest = System.Net.WebRequest.Create(url)
Dim miResponse As System.Net.WebResponse = miRequest.GetResponse
Dim imagenStream As System.IO.Stream = miResponse.GetResponseStream()
Dim miImagenFromStream As Image = Image.FromStream(imagenStream)
Me.PictureBox1.Image = miImagenFromStream
Espero te sirva creo qu eel codigo habla por si solo asi que prueba a ver que pasa.
SALUDOS