Forms Data Controls :: CheckBox Checked Changed Event Is Firing For Every Control Event?

I am facing one strange problem,I have a gridview in which the last two columns have checkboxes and on those checkboxes click event I am doing some database operations.I also have one checkbox that is outside the gridview which actually shows or hides some of the gidview columns.This was all working well but now I have shifted that grid to a user control because I have to use it in two pages.The problem now is,When the page first loads and I click the check box or any control in the page that is outside the grid then it works perfectly.But once I click any of the check box within grid view column then its behavior chages, now even if I click the checkbox that is outside the grid then also the checkbox_CheckedChanged event of the checkbox that is whithin gridview is fired.That checkbox event then behaves something like a page_load event that is called for every page load and for every event with in the page after it is called once.