Be careful, it might be an indication of decreased Page Rank...... how are ur organic traffic behaving ???
Traffic fluctuations usually happen often during summer, its not that rare pal. People go on vacation, people move to other places without internet for vacation, or people just have too much work. Things happen.
Snowbird thank you for suggestion I am already using competitive ad filter Danimal Thank you very much for idea, I will try this. Site is more then 4 years old, traffic is stable only I see problem with google adsense but otherwise other ad networks are doing very well. I see many time google alog. failure to perform. I also see many google things are used manipulatable many times. I See many time people advertise using adwords then take to the page showing adsense advertisements. That is something against the actual businesses or content websites.