[Harley D]

Here is the CORRECT version.. AT LEAST IN MY CASE!

$mgc_cb_evo_js_vars
$mgc_cb_evo_js_script
 
<!-- Javascript popups -->
<div class="yui-skin-sam">
<div id="mgc_cb_evo_chat_popup"></div>
</div>
<div class="yui-skin-sam">
<div id="chatpopupinput" style="visibility: hidden;">
<div class="hd">$vbphrase[mgc_cb_evo_enter_info]</div>
<div class="bd">
<form method="post" action="assets/post.php">
	<div id="mgc_cb_evo_chat_popup_content"></div><input type="text" size="35" id="id_mgc_cb_evo_prompt_input" name="mgc_cb_evo_prompt_input" />
</form>
</div>
</div>
</div>
<!-- / Javascript popups -->
 
<!-- vBulletin Collapse Tricking -->
<div id="collapseobj_mgc_cb_evo" style="$vbcollapse[collapseobj_mgc_cb_evo];"></div>
<!-- / vBulletin Collapse Tricking -->
 
<if condition="THIS_SCRIPT == 'mgc_cb_evo'">
   <script type="text/javascript">var cb_location = "full";</script>
<else />
   <script type="text/javascript">var cb_location = "inc";</script>
</if>
 
<a name="mgc_cb_evo_top" id="mgc_cb_evo_top"></a>
<table class="tborder" cellpadding="$stylevar[cellpadding]" cellspacing="$stylevar[cellspacing]" border="0" width="{$vbulletin->options[mgc_cb_evo_normalmode_width]}" align="center">
<!-- Chatbox Title Row -->
<thead>
   <tr>
      <td class="thead" align ="center" colspan="2">
         <a style="float:$stylevar[right]" href="#mgc_cb_evo_top" onclick="return exec_mgc_cb_evo_collapse();"><img id="collapseimg_mgc_cb_evo" src="$stylevar[imgdir_button]/collapse_thead$vbcollapse[collapseimg_mgc_cb_evo].gif" alt="" border="0" /></a>
         <span id='mgc_cb_evo_title_opened' <if condition="$vbcollapse[collapseobj_mgc_cb_evo] != ''">style='display: none'</if>>
            <span class="normalfont">
            	$vboptions[mgc_cb_evo_title]
            	<if condition="$vbulletin->options['mgc_cb_evo_show_channelname']">
            		$vboptions[mgc_cb_evo_channelname_separator] <span id="mgc_cb_evo_channel_name">&nbsp;</span>
            	</if>
            </span>
         </span>
         <span id='mgc_cb_evo_title_closed' <if condition="$vbcollapse[collapseobj_mgc_cb_evo] == ''">style='display: none'</if>>
            $vboptions[mgc_cb_evo_title]&nbsp;<a href="#mgc_cb_evo_top" onclick="return exec_mgc_cb_evo_collapse();"><img src="$stylevar[imgdir_misc]/menu_open.gif" alt="" border="0" /></a>
         </span>		   	
         &nbsp;<span>[<a href="$vboptions[bburl]/mgc_cb_evo.php?$session[sessionurl]do=view_archives&amp;page=1">$vbphrase[mgc_cb_evo_archives]</a>]</span>
      </td>
   </tr>
</thead>
<!-- / Chatbox Title Row -->
 
<!-- Chatbox inner in opened mode -->
<tbody id="mgc_cb_evo_opened" style="$vbcollapse[collapseobj_mgc_cb_evo]">
   <!-- Announcement -->
   <if condition="!empty($vboptions[mgc_cb_evo_announcement])">
      <tr class="alt1" valign="middle" width="100%">
         <td colspan="2">
            $vboptions[mgc_cb_evo_announcement]
         </td>
      </tr>
   </if>
   <!-- / Announcement -->
 
	<!-- Editor if position above -->
   <if condition="$vboptions[mgc_cb_evo_editor_position] == 0">
		$mgc_cb_evo_editor
	</if>
	<!-- Editor if position above -->
 
	<!-- Chatbox row -->
   <tr class="alt2">
      <td width="100%" colspan="2">      
 
         <!-- Channel icons and chats -->
         <table width="100%" cellpadding="0" cellspacing="2">
            <tr>
            	<if condition="$show['genchan']">
						<td nowrap="nowrap" valign="top" align="$stylevar[left]">
							<div id="channel_gen_on">
								<img id="mgc_cb_channel_gen_on" src="$stylevar[imgdir_misc]/mgc_cb_evo/mgc_cb_gen_channel_sel.gif" width="20px" height="20px" alt="" border="0" title="$vbphrase[mgc_cb_evo_channel_gen]" />&nbsp;
							</div>
							<div id="channel_gen_off" style="display: none;">
								<a href="#mgc_cb_evo_top" onclick="return display_channel(0);"><img id="mgc_cb_gen_off" src="$stylevar[imgdir_misc]/mgc_cb_evo/mgc_cb_gen_channel_nosel.gif" width="20px" height="20px" alt="" border="0" title="$vbphrase[mgc_cb_evo_channel_gen]" /></a>&nbsp; 
							</div>
							<div id="channel_gen_new" style="display: none;">
								<a href="#mgc_cb_evo_top" onclick="return display_channel(0);"><img id="mgc_cb_gen_new" src="$stylevar[imgdir_misc]/mgc_cb_evo/mgc_cb_gen_channel_new.gif" width="20px" height="20px" alt="" border="0" title="$vbphrase[mgc_cb_evo_channel_new]" /></a>&nbsp; 
							</div>
							$channels_bit
						</td>
					</if>
               <td width="100%" colspan="<if condition="$show['genchan']">2<else />3</if>">
               	  <div id="mgc_cb_evo_user_warn" <if condition="empty($warn_msg)">style="display: none;"</if>>$warn_msg</div>
                  <if condition="$vbulletin->options['mgc_cb_evo_separate_special_chats'] == 0">
                    <div style="width:100%; height: {$chatbox_height}px;overflow-y: auto;border: none; z-index: 1;" id="chats_container">
                   	  <table width="95%" align="$stylevar[left]" cellspacing="0">
	  					<tbody id="chats">
                  			<tr>
                  				<td>$vbphrase[mgc_cb_evo_loading]</td>
                  	  		</tr>
                  	  	</tbody>                  		
                  	  </table>                  
                    </div>
                  <else />
                  	<table width="100%">
                  	<tr>
                  	  <td width="75%" align="left">
	                    <div style="width:100%; height: {$chatbox_height}px;overflow-y: auto;border: none; z-index: 1;float: left;" id="chats_container">
    	               	  <table width="95%" align="$stylevar[left]" cellspacing="0">
	  						<tbody id="chats">
            	      			<tr>
                	  				<td>$vbphrase[mgc_cb_evo_loading]</td>
                  		  		</tr>
                  	  		</tbody>                  		
	                  	  </table>                  
    	                </div>
    	           	  </td>
    	           	  <td width="25%" align="left">
                        <div style="width:100%; height: {$chatbox_height}px;overflow-y: auto;border: none; z-index: 1;" id="schats_container">
                     	  <table width="95%" align="$stylevar[left]" cellspacing="0">
	    					<tbody id="schats">
                    			<tr>
                    				<td>&nbsp;</td>
                    	  		</tr>
                    	  	</tbody>                  		
                    	  </table>                  
                        </div>                  	                    
                      </td>
                    </tr>
                    </table>
                  </if>
 
					<!-- Chatbox whosonline in tab -->
					<if condition="$show['mgc_cb_evo_whoisonline'] && $vbulletin->options['mgc_cb_evo_whoisonline_showintab']">
						<div id="collapseobj_mgc_cb_evo_online" style="display: none;width:100%; height: {$chatbox_height}px;overflow-y: auto;border: none; z-index: 1;">
							<strong>$vbphrase[mgc_cb_evo_online_users]</strong> : <span id="mgc_cb_evo_nb_online_users"><if condition="$show['mgc_cb_evo_nouser_online']">0<else />$users_online[nb]</if></span> $vbphrase[mgc_cb_evo_users]
							<span id="mgc_cb_evo_online_users">
								<if condition="!$show['mgc_cb_evo_nouser_online']">
									<br />
									$users_online[list]
								</if>
							</span>
						</div>
					</if>
					<!-- / Chatbox whosonline in tab -->				                  
 
 
               </td>
            </tr>
   		</table>
         <!-- / Channel icons and chats -->   		
      </td>
   </tr>
   <!-- / Chatbox row -->
 
   <!-- Editor if position below -->
	<if condition="$vboptions[mgc_cb_evo_editor_position] == 1">
		$mgc_cb_evo_editor
	</if>
	<!-- / Editor if position below -->
 
	<!-- Who is online in the chatbox -->
	<if condition="$show['mgc_cb_evo_whoisonline'] && !$vbulletin->options['mgc_cb_evo_whoisonline_showintab']">
      <tr class="alt1">
         <td width="100%" colspan="2">
            <strong>$vbphrase[mgc_cb_evo_online_users]</strong> : <span id="mgc_cb_evo_nb_online_users"><if condition="$show['mgc_cb_evo_nouser_online']">0<else />$users_online[nb]</if></span> $vbphrase[mgc_cb_evo_users]
            <span id="mgc_cb_evo_online_users">
               <if condition="!$show['mgc_cb_evo_nouser_online']">
                  <br />
                  $users_online[list]
               </if>
            </span>
         </td>
      </tr>         
   </if>
	<!-- / Who is online in the chatbox -->
</tbody>
<!-- Chatbox inner in opened mode -->
 
<!-- Chatbox inner in closed mode -->
<if condition="($vbcollapse[collapseobj_mgc_cb_evo] == '') || ($vbcollapse[collapseobj_mgc_cb_evo] != '' && !$vboptions['mgc_cb_evo_nbchats_closed'])">
   <tbody id="mgc_cb_evo_closed" style="display:none;">
<else />
   <tbody id="mgc_cb_evo_closed" style="">
</if>
   <tr class="alt2">
      <td colspan="2">
         <div id="chats_last">
           	<table width="95%" align="$stylevar[left]" cellspacing="0">
            	<tbody id="lchats">
            		<tr>
               			<td>$vbphrase[mgc_cb_evo_loading]</td>
            		</tr>
            	</tbody> 	
			</table>            
         </div>
      </td>
   </tr>
</tbody>
<!-- / Chatbox inner in closed mode -->
</table>

So if you have multiple themes and are having the same issue, just make sure this file is correct.