Root Mount Error with 2.0RC1, fine with 1.2.3

[RChadwick]

I've got a Neoware 800MHz thin client, an Intel PCI Dual card, and a Super Talent 2GB Flash disk module (Flash drive with an IDE interface). I installed pfsense 1.2.3 with no problems whatsoever. I never put it into use, so I'm not trying to upgrade it from within pfsense, just flash 2.0RC1 over it. When I boot pfsense 2.0 with either a USB CD drive, or a USB flash drive, I get the following error:

–---------------------------------------------------------------------------------------
Root mount waiting for: usbus3
umass0:0:0 Attached to scbus0
Trying to mount root from cd9660:/dev/iso9660/pfsense
ROOT MOUNT ERROR:
If you have invalid mount options, reboot, and first try the following from
the loader prompt:

set vfs.root.mountfrom.options=rw

and then remove invalid mount options from /etc/fstab.

Loader variables:
vfs.root.mountfrom=cd9660:/dev/iso9660/pfsense
vfs.root.mountfrom.options=ro

Manual root filesystem specification:
  <fstype>:<device>Mount <device>using filesystem <fstype>eg. ufs:/dev/da0s1a
                      eg. cd9660:/dev/acd0
                      This is equivalent to: mount -t cd9660 /dev/acd0 /

?                  List valid disk boot devices
<empty line="">Abort manual input

mountroot>

I have two identical units (One was never flashed with 1.2.3), and it fails on both of them. I'm not a Unix guru. Does anyone have any ideas?</empty></fstype></device></device></fstype>

[cmb]

choose the "Boot from USB" option at the initial boot menu, it's option 3 I think.

[RChadwick]

That did it. Thanks!