netmeg - 2:33 pm on Feb 23, 2013 (gmt 0)
First of all, why aren't you asking support? If I had such a drastic and unexpected drop, I'd be contacting them first thing.
Second of all, it would be pretty bad press for Google to be blatantly falsifying stats to such a degree; I guess nothing is impossible but I'd tend to doubt it. Even if they don't care about us, they do care somewhat about themselves.
Third of all, I don't believe Google has ever promised that all stats were up to date and to the minute. I am quite sure that some clicks take longer to verify than others. It's a HUGE system that has to be checked for fraud multiple times (checking the users, the advertisers and the publishers).
You might invest in some heat map software (you can get it for as low as ten bucks a month - no contract) to see if you can track clicks on your site. If the heat map doesn't show clicks either, then possibly your users aren't clicking, or something is preventing the clicks from registering properly.