Post-installation error on two disks

[Kata Goto]

Hello all,

I am trying to install FreeBSD 9.0 AMD64 on two hard drive disks, I
followed the handbook and I make this configuration :
My two HDD :
 - ada0 : OCZ Vertex 2 40 GB (GPT)
 - ada1 : Western Digital VelociRaptor 150 GB (GPT)

The setup :
Disk    Partition Type  Size  Mountpoint     Label
ada0    freebsd-boot    512K
ada0    freebsd-ufs     25G    /            exrootfs
ada0    freebsd-ufs     26G    /var         exvarfs
ada1    freebsd-ufs     135G  /usr         exusrfs
ada1    freebsd-ufs     4G     /tmp         extmpfs

I commit and the installation ended with no error.
But when I reboot :
could not find file system superblock
the following file system had an unexpected inconsistency
ufs /dev/ada1p2 (/tmp)

I tried many configurations (switching disk/partitions/slices), but the
last partition of my WD fails always.
Is my HDD unsupported, have you got an idea?

For you help,
In advance,
Thanks.