Overlib Tooltip Problems

[Kirk Y]

Hey guys, I'm having some issues with my Overlib Tooltips. I've got a vBPlaza link in my header and I've set it so that if a Guest hovers on it, the Tooltip shows and gives a "Only available for Guests... bla bla" deal. Now, my problem is that the Tooltip shows fine in Firefox, but for some reason it doesn't work in IE.

Here's the code I'm using:
<if condition="$show['guest']">
<td width="89" valign="top"id="vbplazamenu"><a href="javascript:void(0);" onmouseover="return overlib('Sorry, vBPlaza is only available to Registered Users.');" onmouseout="return nd();"><img src="2e_bluebuzz/images/2EVOLVE_Bluebuzz_10.gif" name="Image6" width="89" height="32" border="0"></a></td>
<else />
<td width="89" valign="top"id="vbplazamenu"><a href="$show[nojs_link]#vbplazamenu" onMouseOut="MM_swapImgRestore()" onMouseOver="MM_swapImage('Image6','','2e_bluebuzz/images/2e_Bluebuzz_rollovers_10.gif',1)"><img src="2e_bluebuzz/images/2EVOLVE_Bluebuzz_10.gif" alt="vbPlaza" name="Image6" width="89" height="32" border="0"></a><script type="text/javascript"> vbmenu_register("vbplazamenu", true); </script></td>
</if>

The error I get in IE is: "Unknown runtime error."

If you'd like to take a look at it live: http://forum.socomcity.net
Just mouseover the vBPlaza button in the header.

Thanks in advance for any help you guys can give.