I have an Amilo Pro 3505 laptop and a Spire GigaPod VIII external HDD enclosure with 500GB Samsund disk. It works fine, but when I try to shut down the computer (Win7 if that matters) I cannot reliably do that until the enclosure is plugged in. It seems it somehow back-powers the computer through the USB cable and confuses the BIOS. The laptop only settles down when I unplug the device.
If I replug it when the computer is turned off, it seems it starts a power cycle: the fan starts spinning and the DVD drive plays its initialization moves, but the computer does not display anything nor does not start to do anything else. I have to press the power button for 5 seconds to power down after I removed the cable.
Bottom line, if the enclosure is plugged in, I cannot start or stop the computer. When it is unplugged I can start and stop it correctly. I have to plug it after the boot and unplug it before the shutdown. The drive and the connection works as expected: I can copy files from and to it. (I guess all my USB ports lack of any unidirecting diode on the 5V line?)
What can be the problem?