I know it's unlikely, but maybe there's a flakey [link|http://z.iwethey.org/forums/render/content/show?contentid=208819|switch] in the path from the Win2k machine.
Does the bad Win2k machine have a system name or IP address that conflicts with another Win2k machine? Typo in the [link|http://z.iwethey.org/forums/render/content/show?contentid=184447|hosts] file?
No, I don't think a bad switch would really act the way you describe, or the other things, but when you've checked everything, you have to check something else.
I'm about all tapped out. Luck!
Cheers,
Scott.