The error you get is:
ERROR: Current NTFS volume size is bigger than the device size!
When you go to the parted forum you will be very well guided to solve the problem though.
And so this didn't lead to data loss for me.
Just stay cool and don't start deleting partitions in your panic.
See for details: http://gparted-forum.surf4.info/viewtopic.php?id=14714