I can also concur that USB with 2.0 beta 7 and Win XP is really flaky.
I was getting socket errors, no player available on USB, player disconnected, etc. etc. etc.
If you can, go to ethernet, its faster and much more bombproof.
Just my .02 cents (USD)

Z~
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...all I ask is a tall ship and a star to steer her by.