WARNING!! Mageia LIVE appears to have wiped my hard drive

I say "appears" because this may be some sort of corruption related to this thread: viewtopic.php?f=7&t=4255
Anyway, here's the full story:
I downloaded the live DVD iso and dumped it on to a USB stick using DD. Something I have done countless times without issues and I am 100% sure I have made no errors.
I booted from the USB stick and selected the live boot from the, poked around and generally checked out Mageia for a bit.
Shutdown the computer and removed the USB stick.
About 20 minutes later I turned on the computer to boot into my regular install (kubuntu) and found myself faced with the Live grub menu as seen on the USB stick.
I double-checked the USB wasn't still inserted and sure enough it wasn't and Mageia was booting up and indeed finished at the desktop... with no USB!!
I assumed that somehow the MBR had been corrupted so I tried chrooting into my old partition but the konsole told me there was no partition so I looked at the disk partitioner and sure enough, it showed all my partitions had gone. No more Windows, no more linux partitions (there were 5) and no more data partition with all my music, videos, photos etc.
All the is left is a 1.46GB partition, presumably containing this Mageia image?
I have no idea where to go from here. At best there is some corruption and it only appears that the drive is wiped out. At worst it IS wiped out and I have lost EVERYTHING.
I should point out that at no time whilst running from the live USB did I launch the partition manager or installer or anything at all that should have touched the hard drive.
Just connected to the internet, made sure things were working and stuff.
Where do I go from here?
Anyway, here's the full story:
I downloaded the live DVD iso and dumped it on to a USB stick using DD. Something I have done countless times without issues and I am 100% sure I have made no errors.
I booted from the USB stick and selected the live boot from the, poked around and generally checked out Mageia for a bit.
Shutdown the computer and removed the USB stick.
About 20 minutes later I turned on the computer to boot into my regular install (kubuntu) and found myself faced with the Live grub menu as seen on the USB stick.
I double-checked the USB wasn't still inserted and sure enough it wasn't and Mageia was booting up and indeed finished at the desktop... with no USB!!
I assumed that somehow the MBR had been corrupted so I tried chrooting into my old partition but the konsole told me there was no partition so I looked at the disk partitioner and sure enough, it showed all my partitions had gone. No more Windows, no more linux partitions (there were 5) and no more data partition with all my music, videos, photos etc.
All the is left is a 1.46GB partition, presumably containing this Mageia image?
I have no idea where to go from here. At best there is some corruption and it only appears that the drive is wiped out. At worst it IS wiped out and I have lost EVERYTHING.
I should point out that at no time whilst running from the live USB did I launch the partition manager or installer or anything at all that should have touched the hard drive.
Just connected to the internet, made sure things were working and stuff.
Where do I go from here?