moving IFRAME to top, losing REQUEST.PARAMS

[Bob]

When I move an IFRAME page back to 'top.location'
( eg with some javascript in the page : if (top !=self)
top.location=self.location; )

it appears to be losing the contents of REQUEST.PARAMS.

If I don't move the IFRAME page to top.location and just let it load
in the IFRAME again the REQUEST.PARAMS are there as I want them.
Can anyone explain what's happening, and how I might get around it?
thanks,
Bob

[Bob]

just to add...
My guess is it must be because the javascript is running and loading
the IFRAME page before the iframe page's Page_Load gets to read/write
the request.params from the sending page ( er, if you follow )