Problem downloading from network hard drive

I have a strange problem with my network hard drive. I have a wireless
network with two computers connected to a router, one XP and one vista. I
have also connected a network hard drive to the router. Almost all of it
works just fine, but I can not download files from the hard drive to my vista
computer. I can upload to the hard drive though, and I see all of the folders
and files, but when I try to download them it just won't work. I am able to
log on to the hard drive and if I connect the computer either to the hard
drive or to the router eith a wire it works perfect. I am not able to reach
the Any ideas?