debian does not boot when i have a UUID-entry in fstab (2 replies)

Hi.
I really can't unerstand this.

The debian-dockstar boots and runs without problems.
I can mount (while running) and use an external HDD without problems.
BUT when i reboot the debain only boots when i delete the UUID-entry in the fstab.
It doesn't matter if the HDD is connected or not.

blkid

root@server:~# blkid
/dev/sda1: LABEL="WD" UUID="ac1592e4-c314-0281-5c38-0c46a9b898c4" SEC_TYPE="ext2" TYPE="ext3"
/dev/sdb1: UUID="3f90c7f9-dcd6-442f-87c3-7996a376bc80" TYPE="ext2"
/dev/sdb2: TYPE="swap"

/etc/fstab

# /etc/fstab: static file system information.
#
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
/dev/root      /               ext2    noatime,errors=remount-ro 0 1
/dev/sda2      none            swap    sw                0       0
tmpfs          /tmp            tmpfs   defaults          0       0

#UUID=b9579e0d-4b26-47a8-9ef3-55dd73435846 none swap sw 0 0
UUID=ac1592e4-c314-0281-5c38-0c46a9b898c4 /mnt/WD ext3 defaults 0 2

Can you help me?