Hi i have a prob on my comp

Question

hello sir ,
how r u? alright.. while am surfing my internet suddenly , without my control mouse pointer is going at the left side on the screen and also all of the suddehn some of the operations are activated .. and some files are opening... but ater some seconds, it comes normal..... i do have avg antivirus .. i have scanned many times but still it is not rectified.. so plz help me out with a simple operations....

thanking you your's
nafi