php/java problem (help please is for april fools!)

[Eq4bits]

i have a javascript on a single page of my forum that works with firefox, mozilla, seamonkey, safari, and netscape but NOT IE
when the page loads that has this effect added to it's template
in IE7
there's a notice at the bottom in bar that it is 'Done' but with errors on page
details of error:
Line 356
Char 5
Error Object required
Code 0
then when looking at page source via code editor :
lines 355-358:

PHP Code:
  } else if (ie4up) {
    doc_width = document.body.clientWidth;
    doc_height = document.body.clientHeight;
  }

line 356 being the doc_width code

any assistance would be appreciated
this is for my 'april fools' theme