1. At the top of each page, when you define your dummy functions for HM_f_PopUp and HM_f_PopDown, add the following function declaration:

   function HM_f_PopUp(){return false};
   function HM_f_PopDown(){return false};
   function HM_fc_ClickPop(){return true};

2. Add the following custom function to your pages. Note the simplest way to add it to your pages is to add it to HM_Loader. This must be added at a point below the above dummy functions (or you could simply add this instead of your dummy function. But if you add this function to HM_Loader, it is best that you keep the dummy function declaration as mentioned in step 1):

   function HM_fc_ClickPop(menuid,event) {
      if(typeof(window.HM_f_SetKeyWords)=="undefined") {
         return true;
      }
      else {
         HM_f_HideAll();
         HM_f_PopUp(menuid,event);
         return false;
      }
   }

   Note that if you are using the optimized code set, this function will look like this:

   function HM_fc_ClickPop(menuid,event) {
      if(typeof(window.HM_f_SetKeyWords)=="undefined") {
         return true;
      }
      else {
         HWn();
         HM_f_PopUp(menuid,event);
         return false;
      }
   }

3. Change your link setups--the links that will popup the menu--to look like this:

   <a href="http://hiermenuscentral.com"
      onclick="return HM_fc_ClickPop('hm_menu1',event)"
      onmouseout="HM_f_PopDown('hm_menu1')">HMC</a>
   
   <a href="http://anothersite.com"
      onclick="return HM_fc_ClickPop('hm_menu1',event)"
      onmouseout="HM_f_PopDown('hm_menu1')">HMC 2</a>

4. Finally, set the top level menu(s) that you will be reusing to ClickStart:0. Since you are using onclick, you need to bypass HM's own internal ClickStart behavior, which is what causes the problem in the first place.

For a working example of the above, see this page.