adCenter411, the Microsoft adCenter representative at Search Engine Watch Forums said a bug in the system auto rejected a bulk of keywords a while back. But they are working to fix the issue and reach out to those to resubmit. Here is the message;
Hello everyone, It has come to our attention that, since our last release, some keywords are being erroneously rejected. We are currently looking into the situation and are hoping for quick resolution. If you have submitted keywords on or after November 13th, and received large rejection volume, please be aware that we will reach out with more information soon.
Thanks for your understanding, adCenter411
Pretty big. This goes back to almost last year?
November October 13th? Wow.
Forum discussion at Search Engine Watch Forums.
Update: adCenter411 said that November was a typo. Phew!