If you repeatedly unplug and re-plug a 1394a hard disk on a Windows Vista-based or Windows Server 2008-based computer that has two 1394a hard disks, the other 1394a hard disk becomes inaccessible
On a computer that is running Windows Vista or Windows Server 2008, you have two IEEE 1394a hard disks connected. If you repeatedly unplug and re-plug one of the 1394a hard disks, the other 1394a hard disk becomes inaccessible. Then, you receive a Stop error that resembles the following:
STOP: 0x0000009F (parameter1, parameter2, parameter3, parameter4)
For more information on this issue, including potential causes, workarounds, and resolutions, see: Microsoft KB Article KB960884.