I guess it's caused by missing HDD drivers. (SATA?)
It seems that it's rather hard to include more HDD drivers into BART (e.g. Intel drivers conflict with each other - even when not "used" - and cause bluescreens in BART). We are working on a new version, built on Vista kernel, which will hopefully solve the problem.
In between, you may try to
1. supply the controller driver on a diskette when BART is booting, if you have any
or
2. disable "Native SATA mode" in BIOS before booting BART (and setting it back when you're done with BART, I guess)