UI-Tabs in IE7

UI-Tabs in IE7

Hi

I encountered a weird bug that i don't know how to fix. Searched and tried everything but to no prevail.
I have a asp:dropdownlist inside my ui-Tabs and below the dropdown are many checkboxes (<input type="checkbox"). The weird part is that when i click the dropdown i cannot make selections and it closes quickly. However the dropdown works correctly if:
i)  i move the contents outside of the ui-tab;
ii) i replace <input type="checkbox"> to button, textbox etc
This problem is only happening in IE7. It works in both IE6 and IE8 as well as Firefox.

Can someone please help?

A shortened version of my code:

    <div id="ExchangeEditorTabs" style="display:none">
        <ul>
            <li><a href="#ExchangeEditorTabs-1">Add a new Exchange</a></li>
        </ul>
            <div id="ExchangeEditorTabs-1">  
                    <label class="labels3">Technology</label>
                    <asp:DropDownList ID="ddlAddExchangeTechnology" runat="server" CssClass="dropdownlists" TabIndex="15" ></asp:DropDownList> 
                    <div class="headingRowAnyWidthBlue">
                        <label class="labelsAutoBlue">Actions:</label>
                        <span class="checkBoxCell"><label class="checkboxesText">Select All</label><input type="checkbox" id="chkAddExchangeActionsSelectAll"/></span>
                    </div>
                    <div class="InputAreaAnyWidthBlue">
                        <span class="checkBoxCell"><label class="checkboxesText150px">Create</label><input type="checkbox" class="AddExchangeActions" id="chkAddExchangeActionsCreate"/></span>
                        <span class="checkBoxCell"><label class="checkboxesText150px">Modify</label><input type="checkbox" class="AddExchangeActions" id="chkAddExchangeActionsModify"/></span>
                        <span class="checkBoxCell"><label class="checkboxesText150px">Dismantle</label><input type="checkbox" class="AddExchangeActions" id="chkAddExchangeActionsDismantle"/></span>
                        <span class="checkBoxCell"><label class="checkboxesText150px">Interrogate</label><input type="checkbox" class="AddExchangeActions" id="chkAddExchangeActionsInterrogate"/></span>
                        <span class="checkBoxCell"><label class="checkboxesText150px">Activate</label><input type="checkbox" class="AddExchangeActions" id="chkAddExchangeActionsActivate"/></span>
                    </div>
            </div>
      </div>

Kind Regards
Bee