I just sent an email to support at adwords. I know we were upgraded sometime ago and they give us phone support now, but I can't find the number b/c we've never had a problem before.
For being a premium advertiser who has never complained before, we thought we'd get a little courtesy here, but Google says very bluntly that it must be our fault somehow. I'm very disappointed with their response, and am considering pulling the plug on adwords altogether in favor of Overture.
Seems very strange, imho, that suddenly your site would get such a large spike in traffic that didn't convert.