Have you tried this freeware tool -->
USBDeview - View all installed/connected USB devices on your system? See if you can use it to disconnect your USB device and see if that helps.
I don't have Vista. I have Windows XP and Windows 7 (yip, I avoided Vista for lots of reasons and I'm glad I did and Windows 7 is awsome!). I'll try it on my Windows 7 computer and let you.
What you can try is after you've disconnected your player,
press and hold down on the "M" or "Menu" button and see if that takes you to the main menu so you can use your player.
If that doesn't work, try
turning off your player and turning it back on again (after you've disconnected from Vista).
Let me know if the result.