I tried disabling the Tabstrip on the client side as well as server side and text is not getting disappeared. I am using the latest version of RadControls(2008.3.1314.20). Here is the code which I tried:
CS:
RadTabStrip1.Enabled = false;
You can also disable the text on the client side.
JS:
<script type="text/javascript" >
function DisableTabStrip()
{
var tabStrip=$find('<%=RadTabStrip1.ClientID %>');