Same issue as many. Laacie d2 quadra

Hello,
I have tyhe same issue as many here. I have a Lacie d2 Quadra running on Vista. All has been fine. All of a sudden a couple days ago, the drive dissappeared off the list. It is still listed in EDM but not on the list of drives. Tried many remedies here with similar non results. Oddly, tonight I pluggerd in a SanDisk cruzer card. Next thing I know the Lacie is listed. I checked it out, files werte fine. Then I restarted the computer, ejecting the USB cruzer card first. When the PC rebooted, the drive was gone again. Huh? When I shut down the PC the Blue Lights on that drive stays lit. If it is on when booting, the PC freezes till I turn it off. When the reboot is complete, the drive turned on is listed in DM but again not on the drive list in "Computer". Totally baffled!