I have this mixed network and usually log into the Macs from the Windows XP home machines and vice versa. I have no real networking knowledge, things just seem to work, more or less, with the default settings.

Now I've got a new Snow Leopard Mac with a shared folder (added the user names of the Windows users at the sharing preferences) and the trouble is some machines can open the share and others can't. I can't see the difference.

It feels like some Windows machines have a "cache" and won't ask for the share password, just deny access. I can also see old shares proposed at the Windows "add network place wizard".