If you’ve been running ads on Yahoo! for a while, you might want to look at your historical data. From what I’m seeing, information from before 12/29/09 is no longer available.
Yahoo! is expected to stop serving their own search results at the end of this year. Bing will start supplying search results for them starting in October, in a roll out that will take until the end of Spring, 2011.
Details of what marketers are supposed to do to roll over their accounts haven’t been released, but it appears obvious that the information you may have been keeping on your account status in Yahoo! won’t be available.