Form name complaint on HTML 4.0 Trans

The Validator complaint about the form name I used. Check this website:
http://www.exevior.com 
 
The <form name="f"  is used to parse the JScript "Focus" command on the
search box. After searching through many resources on this resource, and
testing many variables to alternate the use of the <form name="f"  element
for the Jscript I found that it is absolutely correct in HTML 4.0
Transitional, and even though I went through all the other Document types
and corrected my code to match them, none recognised this variable and all
complaint about it.
 
My guess, is a bug in the Validator. Please correct me if I'm wrong, and
send me your recommendations on alternating this at this address:
http://www.exevior.com/support  (I'm not using my email here for obvious
reasons of spamming, thank you for understanding.)
 
Thank you all in advance, for any help you might provide in correcting this
error on my site, or the bug if it is on the Validator.
 
Regards
 
Angel Exevior