You can get the version numbers of your particular tools by typing 'ver' at the Command Line. But again...please seem my comment dated March 8, 2013b below. You can use the Cascade Training GUI to specify ground truth in R2012b, or to use pre-trained detectors--but you'll need to update to R2013a (or later) to train new detectors.
Please see my comment dated Mar 8, 2013, below. What version of the Computer Vision System Toolbox do you have?
@brett: I am using MatLab R2012b but I don't know the version of my computer vision system toolbox.
The background images you sent me do not appear to be corrupt. I don't know if there are others that are corrupt downstream that are triggering these errors, or if something else is going on. You'll have to go into debug mode (try: >> dbstop if warning) and see if you can narrow down the offending image or command. If you see, for example, that you have successfully processed several negative images before the warnings are triggered, that would give you additional information.