AWA explains why a member's AdSense clicks went to zero.
[Link to quote
"I was running a campaign that used to get about 15 daily clicks from searches and 15 from content targeting (adsense). All of a sudden the latter stopped without ant notification from Google. I've made the routine changes in ad text but this should not be the cause.... "
Actually, the changes to your ads explains it, Spaidermen. Whenever you edit an ad, even in a very minor way, it'll pull that ad down from all partner sites - until the revised ad can be reviewed and approved.
Since all Content Targeted impressions and clicks come from partner sites, these stats will go to zero until the ad is approved and on running on partner sites again.
The same is true of Search partner sites too, btw. So you may very well see a decline in clicks and impressions in search as well.