WebmasterWorld members are reporting that they're logging into their Google AdSense accounts due to an addiction that needs to be stopped and are finding that AdSense is reporting much lower clicks. One person in particular said that his ads are showing zero clicks but even had it clicked on by someone "overseas" to see if it was a problem on Google's end).
Everyone agrees that "something is weird" and only martinibuster suggests that you should check your server logs for an indication of what's happening with your ad clicks. Till then, though, on April 17th and on the 18th, this seemed to be a problem. (Ed note: As of this writing -- the 18th at 4PM EST -- this issue hasn't been resolved as no forum members report anything but strangeness.)
Forum discussion continues at WebmasterWorld.
This post was written on April 18th and was scheduled for publication for Monday, April 21st.