I had to fight with them on this. They disallowed my ads for unuseful content. I talked to several people, and they could never actually tell me what that meant. The people I asked just speculated and guessed but had no real idea what it was.
Then they resubmmited and gave me weird answers like redirects, which I used for tracking purposes and other nonsensical reasons I never really understood.
I basically ended up telling the guy to close the ticket because what they were telling me didn't make sense, and we wanted me to call him again to discuss it some more.
It seems dumb to me that they can not precisely tell you what triggered this kind of action. Telling me something is "unuseful" is more than a little bit ironic. I still don't even know if that is an actual word.
It is not worth wasting time with them when they do this. Clearly the people responsible for this stuff are not very good at it. MSN has always had massively uneven enforcement of their policies... In the OP's case and in my case, there is no actual evidence of anything being wrong. I am not trying to skirt any rules or hit any gray areas, I have been running the same ads and landing pages forever.
The way I see it is somebody who didn't know what they were doing flagged some of my keywords, then I went back and protested it, it then went back to the department, and they probably just asked the same guy again to check it, which of course the guy who screwed up the first time is going to validate his own work and the support people are not going to be able to help because they have no idea what is going on.
The first level support for adcenter is much worse than Yahoo! which is pretty disconcerting for the merger.