Hi Paraskumar,
The issue you're describing doesn't sound like anything addthis_widget.js would do. It doesn't take over your first click on the page, but I've seen that before with a user who was using Sweet Captcha. I'm sure there are others beside Sweet Captcha who do things just as nefarious.
Would you be able to share with us the anti-virus software that's pointing at us as a trojan, and the URL it's beeping on? If you're prefer to share this privately, you can email us at help@addthis.com.
Thanks,
Julka