What You are trying to use is a non-standard, Netscape specific externsion to the HTTP-protocol; IE can't (obviously) handle this adressing technique.
What You shoud do is to set the target in the startform call
print $q->startform(-action=>"whatewer.cgi",
-TARGET=>"Top");
Another way to do it is with javascript:
<script language=javascript type="text/javascript">
function speciallink(new) {
parent.frames["top"].document.location = new;
} // -->
</script>
Call it with
onClick="speciallink('Whatever.cgi')"
(The script can be used on anything that supports the onClick event)
I hope this will help ; )
/Wonko