Well, I have been fighting for a while with the damn MTP driver in Windows XP due a strange error trying to connect and synchronize my Creative ZEN V PLUS.
After several updates, reinstallation, and different configurations, I have found the solution uninstalling the latest Windows Media Player v11 and leaving the old (and features similar) WMP v10.
So, if you are experimenting the same problems, now you already know the solution, go for it!