Help: Updating boot support partitions for the volume as required
My external backup usb hard disk (WD 1.5TB) suddenly could not be mounted on my macbook, so i started a disk repair in Disk Utility. And after it shows "The volume XXX appears to be OK" and then volume repair complete, it shows "updating boot support partitiions for the volume as required" and then stuck there until now (i mean, for a whole night!!). I don't know what to do, the fan is spinning very fast, but the process bar seems not to be moving. It shows estimated time: 2 min, but it never moved on. What shall I do at the moment? I can't just erase the disk, all of my information and data is on it. Thanks.
MACBOOK A1278, Mac OS X (10.5.6)