Ipod Nano 4GB Keeps connecting and disconnecting every few seconds

when i plug the nano into a usb port... it shows up everywhere and then disconnects and then reconnects and keeps doing this, therefore i can update my ipod?
Also... the ipod works fine on the xp pc next door so i have to assume its the USB on my pc.
Running Windows Vista RC2

My 80 GB iPod Classic is having the same problem -- when I connect it to the computer, it syncs as it should and then when I attempt to disconnect it, it starts syncing again. It does this no matter whether I disconnect through iTunes or through the desktop (i.e., dragging the iPod icon to the dock to eject it). This never happened before a software update last week. I forget the update but it was something to do with the Intel processor, I think. My date and time was also screwed up but when I woke up this morning that was finally ok.