Hi, guys. I got myself a serious problem here. Last night I used time machine to backup the whole disk to a usb disk (backup file is about 300G). Then I did a clean installation of Lion. I connected the usb disk back to mac and went out. After I came back, what I can find from the usb disk is only a 'small' backup (90G). The old one is gone. All my data are gone now. Can anybody help? The disk is 500G so the old backup should not be deleted anyway.