I had my adCenter campaign on pause, since it wasn't converting and I was paying 2-3X my AdWords cost.
I noticed hits on the bank statement, went to check, and sure enough, the campaign was paused. I hadn't even looked at it for weeks. As commented on other threads, MICROSOFT cannot produce a report to show me the traffic.
They gave me a partial refund, but nowhere near what I was charged.
So...watch them closely if you put a campaign on pause.
I think I'm pretty much done with adCenter. I've been a bit PO'ed because, like so many others, I didn't ever get my "free clicks". I also found evidence of "campaign tweeking", keyword phrases that I would never, ever, buy, with $3.00 + PPC for clicks that should be about a quarter. They told me they'd "never touched it" (my campaign).
And yes, I know I need to watch the bank statement closer. The problem is, Microsoft chose the term adCenter to purposely mirror Google. I'll be darned if I can teach my folks that adCenter isn't Google. :)
[edited by: Lyn99 at 5:49 pm (utc) on Feb. 2, 2007]