A potentially dangerous Request.Form value was detected from the

hi all,
i have tabpanel & inside that one textbox to display some javascript code..

code is like this :
<!-- Begin: CompanyName, Generated: 12/4/2009 12:00:00 AM  -->
 <script language="javascript" type="text/javascript">
 document.write("<iframe width='733' height='120' scrolling='no' frameborder='0' id='txtFrameID' src='http://localhost:3191/code/mb/getad.aspx?AdZoneID=7'></iframe>");  
 </script>
<!-- End: CompanyName -->


When i submit this page & want to save this data then it shows be the error like :
A potentially dangerous Request.Form value was detected from the client (ctl00$ContentPlaceHolder1$TabContainer1$TabGetCode$txtHTML="<!-- Begin: CompanyN...").now what to do to over come from this problem..
i have ...