>>>>I have a weird situation. The Site.master page of my application has a pull-down menu at the top. The menu is built on Bootstrap CSS menu. Right now the first pull-down has 2 items. Each item is an anchor tag that opens a page. What happens is when I click on the second item, the IE 9 popup blocks opening the page (with the message "pop-ups were blockes on this page.. "). Even when I change the items of the menu, moving the first page anchor to the second place and so on, the second is always being blocked. Here is the segment of the menu code:
>>>>
>>>>

>>>><li class="dropdown">
>>>>     <a href="#" data-toggle="dropdown" class="dropdown-toggle">Features<b class="caret"></b></a>
>>>>      <ul class="dropdown-menu">
>>>>             <li><a id="A3" runat="server" href="~/Page1.aspx" target="_blank">Page 1 Feature</a></li>
>>>>             <li><a id="A2" runat="server" href="~/Page2.aspx" target="_blank">Page 2 Feature</a></li>
>>>>             <li><a href="#">Future</a></li>
>>>>             <li class="divider"></li>
>>>>             <li><a href="#">Future</a></li>
>>>>      </ul>
>>>> </li>
>>>>

>>>>
>>>>Why popup blocks just exactly the 2nd item of the menu?
>>>
>>>Weird. AFAIR popup blockers shouldn't kick in if the page is loaded as the result of user interaction (as in your case above).
>>>Don't know if it's relevant but :
>>>Which browser? Are you getting the same behaviour in different browsers ?
>>>Do either of those pages launch another pop-up automatically ?
>>>Do you get the same behaviour if the link goes to a simple, empty HTML page?
>>
>>A Hello Popup simple HTML generates the same popup block. Actually I found that in some other places - randomly - the popup blocks pages. Blocks one second and not 20 seconds later. So I am going to write it off to the quirk of IE 9. And since most of the future customers will be using tablet browser(s), hopefully the problem will go away on its own.
>
>Do you have an add-on popup blocker installed? Maybe try disabling all and any to see if it changes behaviour.....

How do I find out if I have add-on popup blocker installed? Where to look? Could it be something that came with Google toolbar?