Pop up window loosing focus

I have a login form with the following code...

<form method="post" name="logonform" id="logonform"  >
<input type="text"
                  class="text"
                  id="username"
                  name="username"
                  tabindex="100"
                  value="<%=(strUserName == null) ? "username" :strUserName %>"
                  onfocus="if(this.value=='username')this.value = ''"
                  onblur="if(this.value=='')this.value='username'; if(eval(document.logonform.password)){if(password.value=='Password'){ makepassword_form(passwordArea_form); }}"
                  onkeypress="javascript:enterSubmission_form();"
                  <%=readOnly%>
            /><br/>
            
                  <span id="passwordArea_form">
                        <input type="text"
                              class="text"
                              id="password"
                              name="password"
                              tabindex="101"
                              value="Password"
                                                                    onfocus="if(password.value=='Password')makepassword_form(passwordArea_form); "
                              onkeypress="javascript:enterSubmission_form();"
                        />
                  </span>
            
                  <a href="#" onclick="javascript:validate();"><img src="<%=imageUrl%>" border="0" alt="Login" tabindex="102" ></a><br/>
                  <img src="<%=imageBlindUrl%>" height="5" alt="" /><br/>
            
            

In case the user gives incomplete login information such as he only enters the username and leaves the password as blank, an incompleteLogin page needs to be displayed. When the user clicks on the button after giving incomplete information, an incompleteLogin.jsp page is displayed and focus remains on that page  but when user uses the enter key to submit the form, the incomplete login page comes in the background and the main window is displayed. However this happens only for hte first time. If user does the same second time (that is gives incomplete login information and presses enter) the control correctly comes to the incomplete logi page.

Here is the javascript function

      function enterSubmission_form(){
            if (window.event && window.event.keyCode == 13)
            {
                  
                  if(document.logonform.username.value=='null' || document.logonform.username.value=='' || document.logonform.username.value=='username'  || document.logonform.password.value=='' || document.logonform.password.value=='null'  || document.logonform.password.value=='Password')
                  {
                        document.logonform.username.focus();
                        window.open(setCurrentContextLogin+"/controller?action=incompletelogin",'incomplete_Login','toolbar=0,scrollbars=1,statusbar=0,menubar=0,resizable=0,width=600,height=400',"IncompleteLogin");
                        
                  }
                  else {              
                     validate();
               }
            }
      }


Thanks