I was updating my wife's iPhone the other day, which first required me to update iTunes on her Windows 8.1 Lenovo laptop. After the iTunes update, it required a reboot, so I let it do that. But it didn't come back to life. Nothing on the screen, no real noise (like head movement or thrashing or worse) from the hard drive, but it seemed to be spinning. I forced it off, removed the battery for a few moments, reinserted it, then turned it on with the same results. Figured the hard drive had croaked. I bought a housing for a 2.5 inch drive to make it run as an external USB drive and plugged it into my computer to see if it was working. My computer recognized it and I could see all the folders and transferred some files off of it. It seemed fine. So I put it back into the computer and, voila!, it booted. But a couple of days later I tried to reboot it and had the same behavior. This time I left the battery out overnight and reinserted it and turned it on the next morning. Same no-boot behavior. Then I removed the hard drive and put it back in and still it would not boot. Then I put it back into the enclosure, hooked it up to my machine and it worked fine. Installed the drive back into my wife's machine and it booted like a champ. I really haven't encountered this type of thing before. Does anyone have any idea what might be causing this odd behavior? Thanks.