Menu displays on top of thickbox

What kind of menu have you? It´s typical for flash animations and videos in general, otherwise you have to change the z-index of the menu in your CSS. Could you post some more details. I´d say it is not a Thickbox issue.
Best regards

I have the same issue with another CSS menu. Click on "Privacy Policy" in the left menu:
http://www.wsp.nathanhiemstra.com/about/

CSS Menu:
http://www.lwis.net/free-css-drop-down-menu/

Any suggestions would be greatly appreciated!

@superpond
I could not detect anything strange in this example, klicking "Privacy Policy" lead me to http://www.wsp.nathanhiemstra.com/about/privacy-policy/
The only one thickbox window opens with the "Disclaimer" at the very bottom of the site, however no problems experienced.
Could you deliver more concrete explanation?

Here's some captures of the same problem. Thanks! 6.14, Sky theme, thickbox being called by the Splash module.

Rafaeldwan - check your style.css for this:
#navigation li {
border-right:1px solid #DDDDDD;
float:left;
list-style:none outside none;
margin:0;
padding:0;
position:relative;
z-index:999;
}

Change that z-index to 0 or just remove the line altogether. This should fix some other people's issues too.