Mouse automatically scrolls using PS/2 to USB convertor.

Hi, I am using the below product Dell Inspiron 15 (N5010, Early 2010)

This is to inform that I am using PS/2 port to USB port convertor. I am trying to connect both mouse and keyboard (PS / 2 port) in that only keyboard is working fine.

Issue is mouse scroller functions automatically. Without end-users functionality the scroller moves up and down automatically and mouse movement is not functions properly. Please assist me in this regards by providing your solution for this issue.