Try connecting using another USB cable (rare but could be a faulty cable).
https://www.mobileread.com/forums/sho...d.php?p=841910 might be of some help. It initially asks the question about Linux but does offer some good tips about USB ports and cables.
https://www.mobileread.com/forums/showthread.php?t=66098 might offer some more tips with Vista. There has been some discussion with the PEZ and computers using the Intel chipset, do you know if you are running an Intel chipset on your computer?