Did you change the permissions over to the other pc? I don't know too much about it, but I always had to open the files as an administrator with another pc.

Unless the files are corrupted?

If you unplugged the hard drive while the OS updated then most likely it is corrupt, especially if the OS is on that hard drive. Best way to avoid that is not to remove the hard drive but force shut it down then boot it back up.

Also is it a usb, sata, or an esata hard drive? Since I'm thinking it is a sata hardrive.