Sudden Drop in Clickthrough Rate

Without changing anything on my forums site, my clickthrough rate dropped last friday from previous %3.3 to constant %1.1.
For last 6 days it stayed like that and my earnings went down from average of $45/day to average of $13/day.
It mind boggling. Nothing whatsoever changed on my site and it's settings and placement of Google AdSense ads is the same.
Nothing like this happened in two years I am running the forum and it's almost like google changed something.
It's just google adsense clickthrough rate which dropped for last week to one third of what it used to be and it's affecting my earnings in quite a way.
Anyone is experiencing the same, or am I going crazy?
Joe

 

I'd edit that image. Lots of the data is against TOS. Better to be safe than sorry

 

way to break the TOS in graphical style

 

Well, just wanted to illustrate. But you're right, I took off the picture, just to be on the safe side. Anyways, back to the problem, anyone knows what could cause such sudden drop?
Joe

 

Users of the forum got used to the ads and are now ignoring them? Maybe rotate the color of the ads and move them to a new location each week.

 

I came to think of it as well, later realizing that statistically it just can't be the answer.
For two years it won't drop and now all couple of thousands of my users will get bored at the same time?
It's just hard to believe...

 

Have you had any downtime? Has the number of visits per day stayed more or less the same as normal? Could you have lost a couple of good links that were driving traffic or anyhting like that?

 

The ads served must now be less relevant to your visitors.

Pete

 

Yes, one of my sites had a downtime. I had forwarding setup to link from main page to subforums and I have made a mistake. It was down for couple of days.
Problem I see is that the site is not the one which is really generating much of a traffic or the revenue, but they are sharing the same adsense code.
Could that be it?
If that is the case, then it would really be weird answer to the problem.
I fixed the issue today, so we'll see by the end of the day if that was it.

 

Again, this would based on two years of statistics proved to be hard to believe.
Joe

 

Well, let us know how it goes.

 

I will and I very much hope that this is the case.

 

I had the same thing happen to my site... however, as I only started with adsense recently I could not blame my ads... what I realised is that my site went off the google SE radar... where once my site was in the top five suddenly it dropped so far down my daily hits dropped by half...

So after a lot of huffing and a puffing I created a google sitemap, changed my title meta tags and description and voila I am back in the top five in all the major SE under my four important keywords...

Have you checked your SE ranking... and see whether you are listed..

 

Well, regarding sitemaps, go here to read the sotry on how it affected my rating and number of visitors:

http://forums.digitalpoint.com/showthread.php?t=22847

Joe