I have PC-BSD 9.0 x86_64 (XFCE desktop) on my netbook.
When I try to connesct a FAT32 pen-drive, all work without problems: an icon appears for mounting (on my desktop) and, when I click "Execute", a second icon appears (for exploring; meanwhile, firt icon change to "Unmount") and I can explore and work. When I finish, click to execute the first icon and unmount my pen-drive. All good: a quit bizarre, but good.
But, when I attempt to connecti a external HD (NTFS formatted), the mount operation give some error (I don't understood what error preciselly: message tell me only the word "error", no specification). But HD are mounted the same.
But appear empty!
All space is "free space": no files, no directories.
After this, unmount option is impossible: when I execute "unmount", a windows to esplore is open, everytime.
So, I shutdown (in the regulary way) the System and disconnected (when PC was down) my external HD.
After this, connecting with a Windows XP desktop installation, my external HD appear in good state. All files and directories are. Nothing was destroyed. I have lost nothing.
But I ask to myself: are you sure that the NTFS support, on external devices, is really (and in good way) working in PC-BSD 9.0 x86_64 installation?...
My personal experience was not in that direction, I think...