Two days ago we reported on What Would Cause "No Such Link" to Display on adCenter Click? The answer has now been provided at the Search Engine Watch Forums thread by the adCenter rep.
As I suspected, "there was no ad associated to the keyword because there was no keyword destination URL for param1."
So it is good that MSN doesn't send the click to a blank page. I suspect the advertiser isn't charged, but I have not heard from MSN on if that is true or not.
What is disturbing is that there is no error checking in place (or it is not incredibly visible) to prevent an advertiser from leaving the destination URL blank.
Forum discussion at Search Engine Watch Forums.