I experienced this very data feed problem today and actually lost money because of that. I called Ameritrade and the freaking customer service just told me it was not part of their contract to provide accurate data.
Do you factor in external factors when you do your DCF valuations? Did your professor ever tell you to consider external factors such as Subprime and the value of the dollar in your analysis? Why would you recommend RIMM and the banks when you know very well that they are all screwed?