If it's the same thing as he did with mp3scraps .com - i.e., changing Adsense code as I described in my previous post, - it is against the TOS.
There can be too reasons for sudden increase in ctr. Click bombing or due to technical fault less recording of your page impressions. If it is likely that you are click bombed. I advice you follow these steps: 1. Send an email to google telling them that there is some problem with your ctr. Google have a form for this. You can search this in google help. 2. Go to your adsense management and choose the sites where you can display your ads. And make sure the site which is getting too many clicks is not in the list of sites where your ads are displayed 3. Install a tracking script in your site. Some are available for free and easy to use for example statcounter.com. Get the traffic sources from them and see from which ip address you are getting too many clicks. 4. Send the log to the google indicating who is clickbombing. 5. Additionally you can use ip lookup service and get the location of the clicker. 6. And do not allow your site to show ads until and unless google agrees with you and allow you to show ads. This is the only way to prevent banning. Do these steps at earliest, because if you get banned once, then you will loose all your earning plus you will have to appeal for instate your account which can take 2 months or so to restart your account that too if you are able to prove your innocence plus you will not get your earnings back even if you prove your innocence
And don't forget to keep a copy of your logs and your copy of communications with google. You will need them if you had to appeal to adsense. Also, look at the clicks that whether they are coming at the same time or with difference. Or any specific pattern in clicking. And important thing is that, if you are not being click bombed, then every thing is according to tos, then you need not to worry. But it is still a better idea to talk to google
49% ctr ?? i wish .... my site with 200k page view daily and can't even reach 3% CTR, most around 1%-2% if 49% ctr i should have 100k click perday (each click 1 cent, i make 1000 perday)