asp ImageButton shifts to the center of a table cell when clicked the first time

I have an image button (popup help window) which keeps shifting to center of the cell on the first click. I have to chase it to click it. So I am looking for a way make this button image not to move regardless of cell size changes. The cell size for the Icon location changes when the radio options expands (depending on the choice of the radio button option choosen).
here is the image button:
<tr> <div style = "position:absolute" align="left"> <td class="controltextHeadingBorder"> <b>Connectivity?</b> &nbsp <asp:ImageButton runat="server" ImageUrl="/Images/help.png" onClientClick="return windowOpen3()"/> </div> <td class="borderedCell"> <asp:RadioButtonList ID="rblConnectivity" runat="server" RepeatDirection="Horizontal& ...