unable to access windows vista shares in ubuntu 10.04

hi

I am unable to access my shared files from my windows vista laptop on my Ubuntu pc.
I am able to access them on my windows xp machine and both machines are able to view my Ubuntu shares. my network has no passwords and I can see my vista in the network, but it says it needs authorization to access it. I can access my xp shares without authorization.

in simple terms:
Ubuntu to vista works
Ubuntu to xp works
xp to vista works
xp to Ubuntu works
vista to xp works
vista to Ubuntu does not work

thanks in advance.