This is not an offer to dissect why but offer 2 ideas.

1. Read the discussion at http://forums.cnet.com/5208-6127_102-0.html?threadID=381203&tag=forums06;forum-threads

You are discovering a failed area of Windows. Not that it doesn't work but that maybe it needs to be consumerized or "so easy a caveman"...

2. Skip all that and use a memory stick.

Yes, I've fixed this too many times. Too often it's one of the issues noted in item 1, other times it's the security people install or firewalls. And yes you disabled it but then again I've found ZA to interfere even when disabled!
Bob