how to restrict callback event in c#

Question

Hi Team, i have aspx page with code behind in c#,the page has checkbox list which gets pulled dynamically(not static checkbox list), now my concern is once i do the check/uncheck of checkboxes and if i left mouse button then callback is happening which is not required i have verified the code base and there is no activation of callback event from code, check box unselect/selection is fine but if you click left mouse button on any part of the aspx page callback is happening which i dont want to happen.
 
i do not want to raise callback event if i do mouse click on the form, i tried different options to prevent but could not succeed, can some one guide on this
 

Thanks
msr